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Journal of Bacteriology, August 1999, p. 4955-4960, Vol. 181, No. 16
Department of Microbiology and Immunology,
University of British Columbia, Vancouver, British Columbia, Canada
Received 3 March 1999/Accepted 9 June 1999
The stoichiometry of the structural proteins of the photosynthetic
apparatus in purple photosynthetic bacteria is achieved primarily by
complex regulation of the levels of mRNA encoding the different
proteins, which has been studied in the greatest detail in the
puf operon. Here we investigated the transcriptional and
posttranscriptional regulation of the puc operon, which
encodes the peripheral light harvesting complex LHII. We show that,
analogous to the puf operon, a primary transcript encoding
five puc genes is rapidly processed to generate more stable
RNA subspecies. Contrary to previous hypotheses, translational coupling
and regulation of puc transcription by puc gene
products were found not to occur. A putative RNA stem-loop structure
appears to attenuate transcription initiated at the puc
operon major promoter. We also found that a minor
pucD-internal promoter contributes to the levels of a message that encodes the LHII 14-kDa Many species of purple
photosynthetic bacteria contain an integral membrane pigment-protein
light-harvesting complex that is commonly referred to as LHII. X-ray
crystallography of LHII complexes from Rhodopseudomonas
acidophila and Rhodospirillum molischianum revealed
that these crystal structures are rings of eight or nine subunits that
each contain two small proteins (designated The pucBA genes encode the protein components of the LHII
complex and have been cloned and sequenced from several organisms (9, 12, 15). Although there are several alleles of
pucB ( The regulation of expression of puc genes has been studied
in greatest detail in R. capsulatus and R. sphaeroides, with a focus on control of transcription initiation
in response to light intensity and oxygen concentration within a large
promoter-regulatory region located 5' of the pucB gene.
These studies revealed that several regulatory proteins seem to
influence transcription initiation (20, 33).
A variety of puc gene-encoding RNA molecules exists in
R. capsulatus, as revealed by RNA blotting, S1 nuclease
end-mapping, and primer extension (PE) experiments. These appear to
include a 2.4-kb pucBACDE transcript, as well as RNA
molecules that contain only pucBA, pucDE, or
pucE complete sequences (18, 20, 34). It was
proposed that an inverted repeat sequence located between the
pucA and pucC genes encodes an RNA stem-loop
structure that functions to stabilize the pucBA message
(28). Alternatively, since a version of this inverted repeat
efficiently terminated transcription when inserted between the R. capsulatus pufA and pufL genes (7), the
native puc sequence could attenuate transcription to give
rise to abundant 0.55-kb pucBA messages and a much less abundant 2.4-kb pucBACDE transcript. These two possibilities
are not mutually exclusive. The genesis of intermediate-abundance 0.9- to 1.0-kb pucDE and 0.6- to 0.7-kb pucE RNA
segments is even less clear, although it was speculated that these
molecules result from RNase cleavage of the pucBACDE
transcript (18).
Promoter-mapping experiments (using a translationally in-frame
pucE' fusion of puc operon segments to an
Escherichia coli lac'Z allele) confirmed that a strong
promoter is located 5' of pucB (18). However, a
puc'CDE'::lac'Z plasmid produced about 10% of the In this paper, we present the results of puc operon
experiments that utilized gene fusions, high-resolution RNA 5'-end
mappings by PEs, and RNA blot hybridizations with selected probes.
These experiments directly addressed the questions of attenuation in the pucA-to-pucC intergenic region, translational
coupling between pucD and pucE, and the existence
of a promoter in the pucC 3'-to-pucD 5' region
and identified multiple RNase cleavages within the pucBACDE transcript.
Bacterial strains and growth conditions.
The
Escherichia coli strains used for subcloning were the
dam mutant RB404 (6), an hsdR
derivative of C600 (5), and SM10 (25). Strains
SM10 and HB101(pRK2013) (8) were used to transfer plasmids
by conjugation to R. capsulatus. E. coli strains were grown
in Luria broth (24) supplemented with the appropriate
antibiotics at the following concentrations: ampicillin, 200 µg/ml;
tetracycline-HCl, 10 µg/ml.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Transcript Cleavage, Attenuation, and an Internal
Promoter in the Rhodobacter capsulatus puc Operon
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
(PucE) protein.
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
and 
, both of which
span the membrane once), three bacteriochlorophyll molecules, and a
carotenoid (17, 21). The LHII complex functions in
photosynthesis to absorb and transfer light energy to the LHI complex
and thence to the photochemical reaction center, where a cyclic series
of electron and proton transfer reactions initiates. This series of
reactions, which involves the cytochrome b/c1
complex, culminates in the formation of a proton gradient across the
cytoplasmic membrane (22, 27).
protein) and pucA ( protein) genes
in some species, in Rhodobacter capsulatus and R. sphaeroides, a single puc operon contains single copies
of the pucBA genes, followed by the pucC gene. In
R. capsulatus, the pucC gene is followed by the
pucD and pucE genes, yielding the
pucBACDE operon (9, 13). The pucC gene
product has been proposed to enhance either LHII assembly or
pucBA transcription, the pucD gene product
appears to be dispensable, and the pucE gene encodes a
14-kDa protein the function of which is uncertain and which
copurifies with the LHII complex (although the LHII complex in
membranes purified from an R. capsulatus pucE deletion mutant was relatively unstable) (9, 18, 28, 32).
-galactosidase specific activity of a
pucBACDE'::lac'Z fusion, whereas a
puc'DE'::lac'Z fusion yielded less than
1% of the activity obtained with the
pucBACDE'::lac'Z plasmid. These results
were interpreted as suggestive of translational coupling between the
overlapping pucD and pucE reading frames with
transcription readthrough from an adventitious vector promoter and/or
the existence of a second promoter located in the pucC 3' to
pucD 5' region (18).
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
-galactosidase activity determinations in the gene
fusion experiments. The pucBACDE deletion strain 
LHII
(18) was used as the host of puc operon deletion
plasmids for RNA blot analyses.
DNA manipulations, RNA isolation, blot analysis, and probe construction. Standard methods of DNA purification, restriction enzyme digestion, and other DNA modification techniques were used (24).
RNA was isolated from R. capsulatus by the hot-phenol method as previously described (30). Samples were ethanol precipitated and denatured in a buffer containing formaldehyde and ethidium bromide prior to electrophoresis (23). Five micrograms of RNA per lane was run on a 1.4% agarose-formaldehyde gel beside 3 µg of a 0.24- to 9.5-kb RNA ladder (GIBCO-BRL). After electrophoresis, the gel was equilibrated in 0.5× TBE buffer (24) and photographed with UV illumination before electroblotting overnight at 30 V in 0.5× TBE buffer onto a Biotrans nylon membrane (ICN). After blotting, the membrane was dried at 80°C under vacuum and exposed to UV light for comparison with the blotted gel and preblotted gel photograph to ensure that transfer was complete. Hybridization probes using purified DNA fragments were prepared by labelling with [-32P]dATP by the random-primer method
(10). Unincorporated nucleotides were removed by using the
Qiaex DNA purification procedure (Qiagen). The Qiaex eluate in TE
buffer (24) was denatured at 90°C for 10 min and used
directly for hybridization. Blotted membranes were prehybridized in 5×
SSC (1× SSC is 0.15 M NaCl, 0.015 M sodium citrate, pH 7.0)-1%
sodium dodecyl sulfate (SDS)-10 mM EDTA-50% formamide containing 0.5 mg of denatured, sheared salmon sperm DNA per ml for 4 to 8 h at
42°C before addition of the denatured, labelled probe buffer
(24). The blots were hybridized with probes for 18 h at
42°C. After hybridization, membranes were washed twice for 10 to 15 min each time in 2× SSC-1% SDS at room temperature, twice in the
same solution at 50°C for 10 to 15 min each time, and once for 5 min
in 0.2× SSC-1% SDS at 50°C. Blots were then exposed to X-ray film
in a cassette with an intensifying screen at 
75°C for various
lengths of time before development.
The hybridizations with end-labelled oligonucleotides were carried out
at 42°C in hybridization buffer (50% formamide, 10% dextran
sulfate, 1.0 M NaCl, 50 mM Tris-Cl [pH 7.5], 0.2% bovine serum
albumin, 0.2% Ficoll, 0.1% sodium pyrophosphate, 1% SDS, 0.2%
polyvinylpyrrolidone, 0.1 mg of denatured, sheared salmon sperm DNA per
ml). After hybridization, the membranes were washed twice for 10 min
each time at room temperature in 2× SSC, given a 20-min wash in 2×
SSC-1% SDS at 35°C, and then exposed to film as described above. If
necessary, blots were stripped for reprobing in accordance with the
manufacturer's (ICN) recommendation.
Primers used for PEs and RNA blot probes. For approximate locations of oligonucleotides complementary to puc transcripts, see Fig. 2C. The sequences of the oligonucleotides are as follows: ALPE1, 5'-GTCAGTCATTTCAGATGCGTCC-3'; ALPE2, 5'-GCGAGGACATGATGATGGCGAC-3'; ALPE3, 5'-TTGTAGTTGACTTTCGCCA-3'; ALPE4, 5'-GAATACCTTCGCTTTTCAGTTG-3'; ALPE5, 5'-GCGTCCTCCTCGGGTTCAAG-3'; ALPE6, 5'-GCCACGATCAAAATCAACGC-3'; ALPE7, 5'-CGGTCAGTTTCGTCGTCTCC-3'; ALPE8, 5'-GCGAATGGCAGGTACTT-3'; ALPE9, 5'-GCATAAAGCCGTGTGAT-3'; ALPE10, 5'-TCTTCGGTTGCGTTCTCG-3'.
PEs. 32P-end-labelled (24) primers (10 pmol) were mixed with R. capsulatus total RNA (5 µg) from SB1003 cells grown with low aeration and heated to 90°C for 10 min in hybridization buffer (150 mM KCl, 10 mM Tris-Cl, 1 mM EDTA, pH 8.0). This mixture was then incubated at approximately 2°C below the theoretical melting temperature of the specific oligonucleotide for 2 to 3 h. Nucleic acids were then ethanol precipitated and resuspended in the reaction buffer supplied with the reverse transcriptase supplemented with 10 mM dithiothreitol and 0.5 mM each deoxynucleoside triphosphate. One hundred units of Superscript II reverse transcriptase (GIBCO-BRL) was added, and after incubation at 42°C for 1 h, the reaction was phenol extracted and nucleic acids were precipitated with ethanol. The pellet was resuspended in formamide loading buffer (24), heated to 75°C for 5 min, and electrophoresed on an 8% acrylamide-8 M urea gel next to a sequencing ladder obtained with the same primer and plasmid pBACDE as the template, using the Sequenase Version 2.0 DNA Sequencing Kit (USB).
Construction of pucE'::lac'Z
fusions and other plasmids.
The translationally in-frame fusions
of the pucE'-to-lac'Z genes in plasmids pPEZ,
pCEZ, pBEZ, and pHEZ have already been described (18). A
translational frameshift of the pucD coding sequences was
created by cleavage at the BclI site in the fifth codon of
pucD, filling in, and religation. This insertion of four base pairs changed the codon sequence from 5'-GTG ATC ACA-3' to 5'-GTG
ATC GAT CAC A-3', thus creating a stop codon at the 13th codon of
pucD (pBEZ-OOF and pPEZ-OOF). The inverted-repeat sequence located between pucA and pucC is flanked by
intergenic ApaI sites (29), and so it was deleted
by ApaI digestion, followed by religation to create
pPEZSL, and confirmed by DNA sequencing. The
PstI-to-BamHI puc fragments (see Fig.
1) were inserted into the promoter probe vector pXCA601 (1).
The resultant plasmids were transferred to SB1003 by conjugation. The
plasmids pBACDE, pCDE, pC, pD, and pE, which were present
in strain LHII for use in RNA blot experiments, were previously
described (18).
-Galactosidase assays.
-Galactosidase activities were
measured in timed assays in which equal numbers of cells from 20 ml of
low-aeration cultures (ca. 3.7 × 108 CFU/ml) were
resuspended in 1 ml of Z buffer and made permeable with SDS and
chloroform (19). Activities are expressed as percentages of
the specific activity of SB1003(pPEZ), normalized to the numbers of
cells, and all determinations were performed on triplicate samples in
at least two experiments.
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RESULTS |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Transcriptional organization of and attenuation within the
puc operon.
Although it was well established that a
strong puc operon promoter is located 5' of the
pucB gene, promoter mapping of the puc operon
using translational fusions between pucE' and
lac'Z (18) suggested that the region between the
3' end of pucC and the middle of pucD is
important for expression of pucE (Fig.
1; compare the controls pCEZ and pBEZ to
pHEZ). However, it was not clear from these experiments whether this
region contained a minor promoter that contributed to pucE
transcription or if expression of the
pucE'::lac'Z fusion in pBEZ was
enhanced by translational coupling to the overlapping pucD
open reading frame that was abolished when the translational start
region of pucD was deleted in pHEZ. To distinguish between
these two nonexclusive possibilities, we created a stop codon within
pucD in the plasmid pBEZ (to produce pBEZ-OOF), reasoning
that if translational coupling between pucD and
pucE were significant, the -galactosidase activity of
pBEZ-OOF would be similar to the low activity of pHEZ.
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-galactosidase activity of SB1003 cells containing pBEZ-OOF was
essentially the same as that of pBEZ-containing cells (Fig. 1). This
frameshift mutation in the context of the entire operon also did not
significantly affect the level of synthesis of the
PucE::-galactosidase fusion protein (Fig. 1; compare
pPEZ-OOF with pPEZ). These data indicate that there is no translational coupling between pucD and pucE and are consistent
with the idea that the sequence between the 3' region of
pucC and the middle of pucD contains a promoter.
Previous RNA blot analysis indicated the presence of two messages that
contained sequences from the pucBA region. One was the
high-abundance pucBA molecule, and the other was a
relatively low-abundance transcript likely to encode the entire
pucBACDE operon (18). Since there is an inverted
repeat sequence between pucA and pucC, a modified
version of which was shown to encode a strong transcriptional
terminator (7), it was possible that transcription which
originated at the promoter region located 5' of pucB was
greatly attenuated by a rho-independent terminator formed 3'
of pucA. We tested this possibility by deleting the inverted-repeat sequence from pPEZ to produce pPEZSL. The
-galactosidase specific activity measured in cells containing
pPEZSL was higher than that measured from pPEZ (a 23 to 30%
difference), suggesting that a small amount of attenuation occurs at
the inverted repeat between pucA and pucC (Fig.
1). However, this amount of attenuation could not be the sole reason
for the great difference between the steady-state amounts of 0.55-kb
pucBA and 2.4-kb pucBACDE molecules
(18) (and see below). This interpretation is consistent with
the pCEZ and pBEZ results, which showed that the majority of
pucE transcription originates 5' of pucB, but
raises the question of where the residual (10%) expression of the pBEZ
and pBEZ-OOF fusions originates.
5'-end mapping and RNA blots of messages encoding the 3' region of the puc operon. The weak attenuation of transcription in the pucA-to-pucC intergenic region (Fig. 1) and the low abundance of the 2.4-kb pucBACDE transcript (see below) suggested that this primary transcript is rapidly degraded. The pentanucleotide sequence 5'-GNc/uUU-3' was shown to be part of an RNase E substrate in studies of puf operon message cleavage (11). A search of the puc operon sequence revealed the presence of five of these RNase E consensus sites in the pucC coding region and a sixth near the start of pucD (Fig. 2C). In contrast, this motif occurs only twice more in the 3.2-kb sequence reported by Tichy et al. (29), and these two motifs are located upstream of the 5' ends of pucBA transcripts. We therefore performed PE analyses to identify RNA cleavage products and to map the 5' ends of the relatively abundant messages encoding the pucDE region.
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Transcription of pucBA is independent of the
pucC, pucD, and pucE gene
products.
The low amounts of the 2.4-kb transcript encoding
pucC suggest that the PucC protein is present at much lower
levels than the other products of the puc operon. It is
known that the pucC gene is required for accumulation of the
LHII complex (18, 28), and it was reported that a transposon
insertion into pucC, which could exert a polar effect on
transcription of pucDE genes, reduced transcription of
pucBA (28). We tested the effect of independent deletion of pucC, pucD, or pucE, as
well as that of a pucCDE deletion, on pucBA
transcript levels by preparing RNAs from LHII strains that contained
plasmids carrying either the entire pucBACDE operon or
independent deletions of these genes (Fig.
3A). As shown in Fig. 3B, the levels of
the 0.55-kb pucBA transcript were similar in all of the
strains, and so none of the pucCDE genes is required for
transcription of the pucBA genes.
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DISCUSSION |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Previous publications suggested that the regulation of R. capsulatus puc operon mRNA levels was likely to be complex (18, 28). In this work, we investigated the possibilities that transcription attenuation, translational coupling, segmental RNA degradation, and two promoters contribute to puc mRNA levels.
Sequence analysis of the puc operon showed that the pucD and pucE open reading frames overlap, such that the sequence 5'-ATGA-3' contains the putative TGA stop codon of pucD, as well as the ATG start codon of pucE (29). In such cases, translation of the 3' gene is often dependent on translation of the 5' gene (translational coupling) (14). We show here that a translation frameshift mutation in the 5th codon of pucD, which produced a translation stop in the 13th codon, did not affect the expression of pucE'::lac'Z translational fusions. Therefore, it seems that there is no translational coupling between pucD and pucE and the function of pucD remains obscure.
The pucC gene is required for wild type-levels of the LHII complex but is encoded by the low-abundance 2.4-kb puc operon transcript (18). This suggests that the PucC protein is not present in amounts equal to the protein components of the LHII complex and that PucC is likely to have a catalytic rather than a structural role. This interpretation is supported by the fact that LHII crystals from R. acidophila and R. molischianum yielded X-ray diffraction from only the PucB and PucA proteins (17, 21). Although it was previously reported that a transposon insertion into the pucC gene resulted in loss of the pucBA message (28), our results show that neither deletion of pucC, pucD, or pucE nor deletion of pucCDE reduced the level of pucBA mRNA. It is more likely, therefore, that PucC has a posttranslational role in the assembly of the LHII complex, as was proposed for the homologous LhaA protein in LHI assembly (31).
Four RNA species attributed to the puc operon were detected in blots. The largest and least abundant of these is thought to be a primary transcript of 2.4 kb, encoding the entire operon. Although there seemed to be significant attenuation of transcription in the pucA-to-pucC intergenic region, our results suggest that the low abundance of the 2.4-kb transcript is mainly due to endoribonucleolytic cleavage followed by rapid 3'-to-5' exoribonucleolytic degradation. There are five matches to an RNase E recognition consensus sequence (11) in the coding region of pucC and a sixth at the start of the pucD open reading frame. Three of these sites mapped near RNA 5' ends that were detected by primer extension. Only one of them (the 5' end detected with ALPE9 and ALPE5) corresponds to a message stable enough to be detected in an RNA blot, and so we propose that a relatively stable processing product of the 2.4-kb primary transcript is the approximately 0.9-kb RNA that hybridizes to pucDE sequences and which extends from the pucC-to-pucD intergenic region to the predicted rho-independent transcriptional terminator downstream of pucE (29). Consistent with this proposal was the discovery that deletion of sequences from either pucD or pucE reduced the size of this molecule but did not eliminate it.
The most abundant RNA product of the puc operon is the 0.55-kb pucBA message. It was at one time thought that transcription initiating upstream of pucB terminated at the imperfect inverted repeat found between pucA and pucC, since a modified form of this sequence had been shown to terminate transcription when inserted into the puf operon (7, 34). In retrospect, these modifications were not insignificant, as they involved the creation of a perfect inverted repeat and substitution of the 5'-ATTC-3' sequence that follows the native inverted repeat sequence with 5'-TTTT-3' to make it more closely resemble a canonical transcription terminator (7). Our results show that deletion of this native sequence from the puc operon resulted in a small increase of readthrough transcription, and so it seems that some transcripts terminate at this site.
In the R. capsulatus puf operon, an inverted repeat sequence
located between the pufBA and pufLMX genes was
shown to function primarily as a barrier against exoribonucleolytic
digestion (it was calculated that 
25% of pufBA
transcripts terminate at this site [7]). By analogy to
the puf operon, we suggest that most of the pucBA
messages arise from cleavage within the pucC segment of the
2.4-kb primary transcript, followed by exoribonucleolytic degradation
that is greatly slowed by an RNA secondary structure in the region
between pucA and pucC transcript segments. A
minor percentage of transcripts terminates at this RNA stem-loop. This model is consistent with all of the available data, including the
relative steady-state amounts of pucBA and
pucBACDE transcripts, the relative amounts of attenuation
indicated by the pPEZ and pPEZSL constructs, and our identification
of putative RNase E cleavage sites with corresponding RNA 5' ends.
We suggest that the approximately 0.6-kb pucE transcript
detected in RNA blots arises from a minor promoter. We mapped an RNA 5'
end to the middle of the pucD sequence, where there is no
RNase E consensus sequence, and inspection of the 10 to 35 region
5' of this end revealed the sequence
5'-CTCAAG-N17-CAGCGC-N10-3', which has weak similarity to
proposed 
70 promoters (20). Furthermore,
deletion of this region from the pBEZ fusion construct (to produce
pHEZ) reduced -galactosidase levels from 10% to <1% of pPEZ and
this 0.6-kb transcript was absent from a pucD deletion
strain that lacked this proposed promoter region. This molecule was not
detected in the pucE deletion strain, but most of the
sequence complementary to the probe used is absent from this mutant.
Taken together, these results indicate that the 0.6-kb pucE
transcript is the product of a secondary promoter internal to
pucD.
Our model of puc RNA regulation is summarized in Fig. 4. The majority of puc transcription initiates 5' of pucB and terminates at the inverted repeat located immediately 3' of pucE, with a small amount of attenuation at the inverted repeat between pucA and pucC. The 2.4-kb primary transcript is rapidly degraded by RNase E endoribonucleolytic and subsequent 3'-to-5' exoribonucleolytic activities. The relatively stable products of this processing are the 0.55-kb pucBA and 0.9-kb pucDE messages. A minor promoter within pucD generates the 0.6-kb pucE message.
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The stoichiometry of R. capsulatus LHI and reaction center
protein components of the photosynthetic apparatus is maintained primarily through complex regulation of the steady-state amounts of
puf operon mRNA segments encoding these proteins. The
cellular mechanisms operative include regulation of transcription
initiation, differential susceptibilities of specific message segments
to endo- and exoribonuclease activities, and transcriptional
readthrough from upstream operons ("superoperons") (2, 3,
16). Our results suggest that puc operon gene
expression is governed by the first two of these mechanisms and that
the stoichiometry of the LHII 14-kDa protein (PucE) is achieved in
part by transcription initiation at a pucD internal promoter.
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ACKNOWLEDGMENTS |
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We thank Grace Wong for expert technical assistance in the construction of plasmid pPEZ-OOF.
This research was supported by grants from the NSERC (Canada) to J.T.B.
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FOOTNOTES |
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* Corresponding author. Present address: Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142. Phone: (617) 258-5242. Fax: (617) 258-9872. E-mail: leblanc{at}wi.mit.edu.
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REFERENCES |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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| 1. |
Adams, C. W.,
M. E. Forrest,
S. N. Cohen, and J. T. Beatty.
1989.
Structural and functional analysis of transcriptional control of the Rhodobacter capsulatus puf operon.
J. Bacteriol.
171:473-482 |
| 2. | Bauer, C. E., and T. H. Bird. 1996. Regulatory circuits controlling photosynthesis gene expression. Cell 85:5-8[Medline]. |
| 3. | Beatty, J. T. 1995. Organization of photosynthesis gene transcripts, p. 1209-1219. In R. E. Blankenship, M. T. Madigan, and C. E. Bauer (ed.), Anoxygenic photosynthetic bacteria. Kluwer Academic Publishers, Dordrecht, The Netherlands. |
| 4. | Beatty, J. T., and H. Gest. 1981. Generation of succinyl-coenzyme A in photosynthetic bacteria. Arch. Microbiol. 129:335-340. |
| 5. | Bibb, M. J., and S. N. Cohen. 1982. Gene expression in Streptomyces: construction and application of promoter-probe plasmid vectors in Streptomyces lividans. Mol. Gen. Genet. 187:265-277[Medline]. |
| 6. |
Brent, R., and M. Ptashne.
1980.
The lexA gene product represses its own promoter.
Proc. Natl. Acad. Sci. USA
77:1932-1936 |
| 7. | Chen, C.-Y. A., J. T. Beatty, S. N. Cohen, and J. G. Belasco. 1988. An intercistronic stem-loop structure functions as an mRNA decay terminator necessary but insufficient for puf mRNA stability. Cell 52:609-619[Medline]. |
| 8. | Ditta, G., T. Schmidhauser, E. Yakobsen, P. Lu, X.-W. Liang, D. R. Finlay, D. Guiney, and D. R. Helinski. 1985. Plasmids related to the broad host range vector, pRK290, useful for gene cloning and for monitoring gene expression. Plasmid 13:149-153[Medline]. |
| 9. | Drews, G., and J. R. Golecki. 1995. Structure, molecular organization, and biosynthesis of membranes of purple bacteria, p. 231-257. In R. E. Blankenship, M. T. Madigan, and C. E. Bauer (ed.), Anoxygenic photosynthetic bacteria. Kluwer Academic Publishers, Dordrecht, The Netherlands. |
| 10. | Feinberg, A. P., and B. Vogelstein. 1983. A technique for radiolabeling DNA restriction fragments to high specific activity. Anal. Biochem. 132:6-13[Medline]. |
| 11. | Fritsch, J., R. Rothfuchs, R. Rauhut, and G. Klug. 1995. Identification of an mRNA element promoting rate-limiting cleavage of the polycistronic puf mRNA in Rhodobacter capsulatus by an enzyme similar to RNase E. Mol. Microbiol. 15:1017-1029[Medline]. |
| 12. | Germeroth, L., H. Reilander, and H. Michel. 1996. Molecular cloning, DNA sequence and transcriptional analysis of the Rhodospirillum molischianum B800/850 light-harvesting genes. Biochim. Biophys. Acta 1275:145-150[Medline]. |
| 13. | Gibson, L. C. D., P. McGlynn, M. Chaudhri, and C. N. Hunter. 1992. A putative coproporphyrinogen III oxidase in Rhodobacter sphaeroides. II. Analysis of a region of the genome encoding hemF and the puc operon. Mol. Microbiol. 6:3171-3186[Medline]. |
| 14. | Gold, L., and G. Stormo. 1987. Translational initiation, p. 1302-1307. In F. C. Neidhardt, J. L. Ingraham, K. B. Low, B. Magasanik, M. Schaechter, and H. E. Umbarger (ed.), Escherichia coli and Salmonella typhimurium: cellular and molecular biology. American Society for Microbiology, Washington, D.C. |
| 15. | Hagemann, G. E., E. Katsiou, H. Forkl, A. C. J. Steindorf, and M. H. Tadros. 1997. Expression of the puc operon from Rhodovulum sulfidophilum. Biochim. Biophys. Acta 1351:341-358[Medline]. |
| 16. | Klug, G. 1995. Post-transcriptional control of photosynthesis gene expression, p. 1235-1244. In R. E. Blankenship, M. T. Madigan, and C. E. Bauer (ed.), Anoxygenic photosynthetic bacteria. Kluwer Academic Publishers, Dordrecht, The Netherlands. |
| 17. | Koepke, J., X. Hu, C. Muenke, K. Schulten, and H. Michel. 1996. The crystal structure of the light-harvesting complex II (B800-850) from Rhodospirillum molischianum. Structure 4:581-597[Medline]. |
| 18. |
LeBlanc, H. N., and J. T. Beatty.
1993.
Rhodobacter capsulatus puc operon: promoter location, transcript sizes and effects of deletions on photosynthetic growth.
J. Gen. Microbiol.
139:101-109 |
| 19. |
Manoil, C.
1991.
Analysis of membrane protein topology using alkaline phosphatase and -galactosidase.
Methods Cell Biol.
34:61-75[Medline].
|
| 20. |
Nickens, D. G., and C. E. Bauer.
1998.
Analysis of the puc operon promoter from Rhodobacter capsulatus.
J. Bacteriol.
180:4270-4277 |
| 21. | Papiz, M. Z., S. M. Prince, A. M. Hawthornthwaite-Lawless, G. McDermott, A. A. Freer, N. W. Isaacs, and R. J. Cogdell. 1996. A model for the photosynthetic apparatus of purple bacteria. Trends Plant Sci. 1:198-206. |
| 22. |
Prince, R. C.
1990.
Bacterial photosynthesis: from photons to p.
Bacteria
12:111-149.
|
| 23. | Rosen, K. M., E. D. Lamperti, and L. Villa-Komaroff. 1990. Optimizing the Northern blot procedure. BioTechniques 8:398-403[Medline]. |
| 24. | Sambrook, J., E. F. Fritsch, and T. Maniatis. 1989. Molecular cloning: a laboratory manual, 2nd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. |
| 25. | Simon, R., U. Priefer, and A. Pühler. 1983. A broad host range mobilization system for in vivo genetic engineering: transposon mutagenesis in Gram-negative bacteria. Bio/Technology 1:37-45. |
| 26. | Solioz, M., and B. Marrs. 1977. The gene transfer agent of Rhodopseudomonas capsulata. Arch. Biochem. Biophys. 181:300-307[Medline]. |
| 27. | Sundström, V., and R. van Grondelle. 1995. Kinetics of excitation transfer and trapping in purple bacteria, p. 349-372. In R. E. Blankenship, M. T. Madigan, and C. E. Bauer (ed.), Anoxygenic photosynthetic bacteria. Kluwer Academic Publishers, Dordrecht, The Netherlands. |
| 28. |
Tichy, H. V.,
K. U. Albien,
N. Gadon, and G. Drews.
1991.
Analysis of the Rhodobacter capsulatus puc operon the pucC gene plays a central role in the regulation of LHII (B800-850 complex) expression.
EMBO J.
10:2949-2955[Medline].
|
| 29. |
Tichy, H. V.,
B. Oberlé,
H. Stiehle,
E. Schiltz, and G. Drews.
1989.
Genes downstream from pucB and pucA are essential for formation of the B800-850 complex of Rhodobacter capsulatus.
J. Bacteriol.
171:4914-4922 |
| 30. |
von Gabain, A.,
J. G. Belasco,
J. L. Schottel,
A. C. Y. Chang, and S. N. Cohen.
1983.
Decay of mRNA in Escherichia coli: investigation of the fate of specific segments of transcripts.
Proc. Natl. Acad. Sci. USA
80:653-657 |
| 31. |
Young, C. S., and J. T. Beatty.
1998.
Topological model of the Rhodobacter capsulatus light-harvesting complex I assembly protein LhaA (previously known as ORF1696).
J. Bacteriol.
180:4742-4745 |
| 32. |
Young, C. S.,
R. C. Reyes, and J. T. Beatty.
1998.
Genetic complementation and kinetic analyses of Rhodobacter capsulatus ORF1696 mutants indicate that the ORF1696 protein enhances assembly of the light-harvesting I complex.
J. Bacteriol.
180:1759-1765 |
| 33. |
Zeilstra-Ryalls, J.,
M. Gomelsky,
J. M. Eraso,
A. Yeliseev,
J. O'Gara, and S. Kaplan.
1998.
Control of photosystem formation in Rhodobacter sphaeroides.
J. Bacteriol.
180:2801-2809 |
| 34. |
Zucconi, A. P., and J. T. Beatty.
1988.
Posttranscriptional regulation by light of the steady-state levels of mature B800-850 light-harvesting complexes in Rhodobacter capsulatus.
J. Bacteriol.
170:877-882 |
Journal of Bacteriology, August 1999, p. 4955-4960, Vol. 181, No. 16
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