Department of Microbiology and Molecular
Genetics, Harvard Medical School, Boston, Massachusetts
02115,1 and Bacterial Diseases
Group, Tularik Inc., South San Francisco, California
940802
 |
TEXT |
The Arc two-component signal
transduction system of Escherichia coli regulates the
expression of more than 30 operons, depending on the redox conditions
of growth (20, 22, 30, 31). The system consists of ArcB, the
membrane-bound sensor kinase, and ArcA, the cognate response regulator.
ArcB (17, 23, 27, 48) (see Fig.
1A) belongs to the tripartite sensor
kinase subfamily (1, 16, 25, 35, 37, 44, 49), is attached to
the cytoplasmic membrane by two transmembrane segments (TM1 and TM2) near the N-terminal end (24), and catalyzes a phosphorelay
via His292, Asp576, and His717 of ArcB to Asp54 of ArcA
(14). The autophosphorylation step is stimulated by
effectors, such as D-lactate, pyruvate, and acetate. These
metabolites accumulate when exogenous electron acceptors limit
respiration during growth (13, 18). Dephosphorylation of
ArcA-P occurs by a reverse phosphorelay from the Asp54 of ArcA to the
His717 and Asp576 of ArcB. The phosphoryl group is then released as
Pi (12).
View larger version (27K):
[in this window]
[in a new window]
|
FIG. 1.
The ArcB sensor kinase and its transmembrane topology.
(A) Schematic representation of ArcB. The putative leucine zipper
(12) and the PAS domain (46) are based on amino
acid sequence homology. The primary transmitter domain contains the
conserved His292 and the catalytic determinants N, G1, and G2. The G1
and G2 sequences typify nucleotide-binding motifs. The receiver domain
contains the conserved Asp576, and the secondary transmitter domain
contains the conserved His717. (B) Schematic representation of ArcB
transmembrane topology. Arrows point to ArcB-PhoA fusions constructed
according to a two-step PCR procedure (41). The first PCR
amplifications were performed, using plasmid pBB25 (23) as a
template and BPH-N and either BPH-22, BPH-41, BPH-57, or BPH-102 as
primers (Table 2). Each purified product was used as a primer with
BPH-C for the second PCR, using the plasmid pDHB5747 that bears
phoA (D. Boyd, unpublished data) as a template. The second
PCR products were digested with BamHI and
HindIII and cloned between the corresponding sites of
vector pUC18, resulting in pBP22
( [arcB1-22-'phoA]), pBP41
([arcB1-41-'phoA]), pBP57
([arcB1-57-'phoA]), and pBP102
([arcB1-102-'phoA]). Each
(arcB'-'phoA) plasmid was transformed into strain DHB4
( phoA) and assayed for alkaline phosphatase activity as
described previously (6). The alkaline phosphatase activity
units are represented by numbers in parentheses and are averages of
four experiments, with standard deviations of less than 10%.
|
|
Most sensor kinases receive their signal from the periplasmic domain,
resulting in conformation changes that trigger autophosphorylation. As
a sensor kinase, ArcB is unusual in having a short putative periplasmic
bridge (24, 29). Relatively little is known about the nature
of the signal for ArcB and what role the membrane-associated region
plays in signal reception, except that autophosphorylation seems to be
activated by excessive reducing equivalents (7, 11, 21, 22, 24,
38). Two studies involving growth of cells at high pH and
treatment of cells by protonophores during growth, however, led to the
suggestion that ArcB kinase is activated by a decrease in proton motive
force (PMF) across the cytoplasmic membrane (2, 5). Here, we
confirm the transmembrane topology of ArcB by genetic analysis and
probe the function of the membrane region by replacing the chromosomal
arcB+ by a single copy of a mutant allele (Fig.
2; Tables 1
and 2).
View larger version (27K):
[in this window]
[in a new window]
|
FIG. 2.
Construction of strains. (A) To construct the
arcB::Tetr strain, the 5'- and
3'-flanking DNA fragments of arcB (fragments 1 and 2) were
prepared by PCR, using chromosomal DNA from strain MC4100 as template
and, respectively, the primer pairs DAB-5N/DAB-5C and DAB-3N/DAB-3C
(Table 2). The products were cloned into pUC18. A Tetr
cassette isolated from pNK81 (50) was then inserted between
the two arcB-flanking fragments, generating pDB3. This
plasmid was transformed into strain JC7623 (36) to create
arcB::Tetr strain (ECL5000) by
homologous recombination. The
arcB::Tetr allele was then P1
transduced into strain ECL5002 or ECL5003, respectively, resulting in
ECL5004 and ECL5012. (B) To introduce the modified arcB
sequence into the arcB::Tetr
strain, the 5'- and 3'-flanking DNA fragments of arcB
(fragments 3 and 4) were prepared by PCR, using chromosomal DNA from
strain MC4100 as template and, respectively, the primer pairs
IAB-5N/IAB-5C and IAB-3N/IAB-3C (Table 2). The products were cloned
into pBluescript KS II(+). A Kanr cassette, isolated from
pUC4-KIXX (3), was then inserted between the two
arcB-flanking fragments, generating pIB3. The 5'-flanking
fragment includes the arcB promoter, ribosome-binding site,
and introduced NdeI site which included the initiation codon
of arcB followed by a HindIII site. Modified
arcB sequences (arcB*) were cloned into the
pIB3 between the NdeI site and HindIII site,
generating pIB*. This plasmid was transformed into strain ECL5000 to
replace arcB::Tetr allele with
arcB*::Kanr by homologous
recombination. Recombinants were selected by the Tets
Kanr Amps phenotype and confirmed by the PCR.
The arcB*::Kanr was then P1
transduced into strains ECL5004 or ECL5012. Not illustrated is the
construction of the reporter fusions. To construct the
(cydA'-lacZ) operon fusion, a 1.0-kb
BamHI-EcoRI fragment of plasmid pBTKScyd1
(31) was ligated into
BamHI-EcoRI-digested lacZ operon
fusion vector pRS528 (42), resulting in pCAZ1. To generate
the (lldP'-lacZ) operon fusion, a 3.6-kb
PstI-BamHI fragment of plasmid pLCT2
(9) was subcloned into pBluescript SK( ) (Stratagene),
resulting in pLLD2. A 0.8-kb EcoRI-BglII fragment
of pLLD2 was then ligated into the
EcoRI-BamHI-digested lacZ operon
fusion vector pRS415 (42), resulting in pLPZ1. The
(cydA'-lacZ) and (lldP'-lacZ) were then
transferred to the  transducing phage RS45 (42),
yielding, respectively, CAZ1 and LPZ1. Lysates with high titers
of CAZ1 and LPZ1 were used to lysogenize strain MC4100, and
single lysogens were selected (28), yielding, respectively,
strains ECL5001 and ECL5003. The
fnr::Tn9 (Cmr) allele of
strain JRG1728 (43) was P1 transduced into strain ECL5001
(yielding strain ECL5002) in order to avoid the transcriptional
repression of (cydA'-lacZ) by Fnr (8).
|
|
Transmembrane topology of ArcB.
To test the suggested topology
based on hydrophobicity analysis, we constructed four phoA
protein fusions (32) of arcB (Fig. 1B). The PhoA
fusions at residues 22 and 102 of ArcB exhibited very low levels of
alkaline phosphatase activity. In contrast, the PhoA fusions at
residues 41 and 57 of ArcB showed very high levels of the enzyme
activity (Fig. 1B). On the basis of this genetic analysis and a more
recent algorithm for determining membrane-spanning regions
(40), we suggest that a periplasmic bridge of ArcB is flanked by TM1 delimited by residues 23 to 41 and TM2 delimited by
residues 58 to 77.
Testing the periplasmic His47 as a possible PMF sensor.
In
order for ArcB to sense 
H+, at least one
amino acid residue on each side of the plasma membrane with pK values
within biological range would be required. The only periplasmic
candidate would be His47. We therefore tested the phenotypes of
His47Gln and His47Arg on the expression of positively controlled
::(cydA'-lacZ) or negatively controlled
::(lldP'-lacZ) (8, 19).
Neither substitution resulted in any significant change in the
expression of (cydA'-lacZ) or (lldP'-lacZ)
(data not shown).
Testing the amino acid sequence of membrane regions.
To
examine the function of various segments of the ArcB membrane region,
we replaced them by a corresponding section of MalF (a subunit of
maltose permease). MalF was chosen because its periplasmic bridge
between the first and second transmembrane segments is also short
(45) and because of the lack of any sequence homology with
ArcB. In each hybrid construct, a portion of the ArcB N terminus was
retained (Fig. 3 and
4). The reason for this measure is that when the cytosolic N-terminal segment of ArcB was replaced by the
corresponding segment of MalF, the level of the hybrid protein diminished in the cell extract, as assayed by Western analysis (data
not shown).
View larger version (39K):
[in this window]
[in a new window]
|
FIG. 3.
Effects of substituting segments of ArcB with MalF
on the expressions of (cydA'-lacZ) and
(lldP'-lacZ). To construct
(arcB1-22-malF17-35-arcB42-778),
PCR was performed with pIBW as a template and BPH-N and BMF-22 as
primers. The purified PCR product and BMF-35 were used as primers for
the second PCR with pDHB32 (6) as a template. The PCR
product and B3NRU were used as primers for a third PCR with the pABW as
a template. The product was digested with NdeI and
NruI and cloned between the corresponding sites of the
pIBW, resulting in pIBM1. To construct
(arcB1-57-malF40-58- arcB78-778),
PCR was performed with pIBW as a template and BPH-N and BMF-40 as
primers. The purified PCR product and BMF-58 were used as primers for
the second PCR with pDHB32 as a template. The PCR product and B3NRU
were used as primers for a third PCR with the pABW as a template. The
product was digested with NdeI and NruI and
cloned between the corresponding sites of the pIBW, resulting in pIBM2.
To construct a
(arcB1-22-malF17-39-arcB58-778),
PCR was performed with pIBW as a template and BPH-N and BMF-22 as
primers. The purified PCR product and BMF-39 were used as primers for
the second PCR with pDHB32 as a template. The PCR product and B3NRU
were used as primers for a third PCR with pABW as a template. The
product was digested with NdeI and NruI and
cloned between the corresponding sites of the pIBW, resulting in pIBM3.
Plasmids pIBM1, pIBM2, and pIBM3 were used to integrate the modified
arcB sequences into the chromosome of the reporter-bearing
strains by the gene replacement techniques, as described in the legend
of Fig. 2. For the  -galactosidase activity assay, the
(cydA'-lacZ)-bearing strains were cultured in buffered
Luria-Bertani broth containing 0.1 M MOPS (morpholinepropanesulfonic
acid) (pH 7.4) and 20 mM D-xylose. For the growth of
(lldP'-lacZ)-bearing strains, the above medium was
supplemented with 20 mM L-lactate as an inducer
(9). The data are averages of four experiments and the
standard deviations are indicated. The different alleles of
arcB are shown as follows: 1, arcB+;
2, (arcB1-22-malF17-35-arcB42-778);
3, (arcB1-57-malF40-58-arcB78-778);
4, (arcB1-22-malF17-39-arcB58-778);
5, arcB. The topology of the chimeric proteins is
illustrated at the bottom: solid segments represent ArcB sequences, and
hatched segments represent MalF sequences. Solid bars, aerobically
grown cells; hatched bars, anaerobically grown cells.
|
|
View larger version (17K):
[in this window]
[in a new window]
|
FIG. 4.
Membrane association of the ArcB-MalF hybrid proteins.
Cultures grown aerobically in Luria-Bertani broth were harvested during
mid-exponential growth. The cells were washed with buffer S (50 mM
Na-phosphate [pH 7.8], 300 mM NaCl, and 1 mM EDTA) by centrifugation.
The cell pellet was resuspended in 3 ml of the same buffer and
disrupted by sonication. Cell debris was removed by centrifugation for
10 min at 4,000 × g. The supernatant fluid was again
centrifuged for 45 min at 35,000 × g to separate the
cytosolic (C) and the membrane (M) fractions. The resultant supernatant
fluid containing the soluble proteins was collected. The remaining
pellet was resuspended in 0.5 ml of buffer M (20 mM HEPES [pH 7.5],
50 mM KCl, 1 mM EDTA, and 50% glycerol). Samples of cytosolic and
membrane (containing 10 µg of protein) fractions were analyzed by
sodium dodecyl sulfate-polyacrylamide gel electrophoresis (12%
polyacrylamide gel) and the proteins were transferred to a Hybond-ECL
filter (Amersham). The filter was equilibrated in TTBS buffer (25 mM
Tris, 150 mM NaCl, and 0.05% Tween-20) for 10 min and incubated in
blocking buffer (0.5% bovine serum albumin in TTBS) for 1 h at
37°C. ArcB polyclonal antibodies raised against
His6-ArcB78-520 were added at a dilution of
1:10,000 to the filter and incubated for 1 h at room temperature.
The bound antibody was detected by using anti-rabbit immunoglobulin G
antibody conjugated to horseradish peroxidase and the ECL detection
system (Amersham). The topology of the chimeric proteins is depicted:
solid segments represent ArcB sequences, and hatched segments represent
MalF sequences.
|
|
When TM1 alone or TM1 plus the periplasmic bridge of ArcB was replaced
by the counterparts of MalF, the expression of
(cydA'-lacZ) was increased under both aerobic and
anaerobic growth conditions (Fig. 3). As to be expected, the
expression of (lldP'-lacZ) was partially repressed
aerobically. However, because anaerobic repression of
(lldP'-lacZ) was already severe in the wild-type
background, further repression by the chimeric ArcB proteins was not
readily discernible. When TM2 was replaced, no significant changes in the expression of either reporter fusion were observed. When TM1, the
periplasmic bridge, and TM2 were all replaced by the corresponding MalF
region, the protein became inactive as an ArcA kinase (data not shown).
However, the lack of kinase activity is difficult to interpret for the
following reasons. First, there may be a failure in signal reception.
Second, there may be a serious conformational distortion. Third, the
protein may fail to dimerize, which is believed to be necessary for
signal transmission. It might also be mentioned that when ArcB is
liberated from membrane association by removal of the transmembrane
domain, the truncated protein becomes constitutively active as an ArcA
kinase (data not shown). This is to be expected, since purified
ArcB78-778 has been shown to be highly active in vitro as
an ArcA kinase and phosphatase (12, 14).
To ascertain that each ArcB-MalF hybrid protein remains membrane
associated, we performed Western blot analysis on cytosolic and
membrane fractions of the cells. In all cases, the hybrid proteins were
found to be associated with the cytoplasmic membrane (Fig. 4).
Discussion and conclusion.
Most sensor kinases have a
periplasmic domain of substantial size flanked by two TM segments for
sensing signals (10, 15, 26, 33, 34, 37, 47). For many
sensor kinases, however, the true signal and its input site on the
protein remain unknown. According to the PMF sensing model by ArcB
(2, 5), anaerobic growth diminishes the energy yield,
thereby diminishing the H+, and activates
the kinase. Results of His47 replacement experiments deprive this model
of an obvious mechanism. It might be recalled that PMF was suggested as
the signal primarily on the basis of protonophore effects on target
gene expression. The validity of the conclusion, however, is
compromised by the severe growth inhibition. Also, from a theoretical
point of view, H+ seems not to be ideal as
a signal, since its level is likely to be homeostatically controlled by
the FoF1-ATPase. Moreover, even during aerobic
growth, the energy source may become limiting. The resultant drop in
PMF would repress the tricarboxylic acid cycle and the electron
transport system in a situation when derepression would help to enhance
the substrate-scavenging power of the starving cell.
The lack of evidence for the PMF model redirected our focus on the
redox model and the possible functional importance of the membrane-associated portion of ArcB for signal reception. Three kinds
of mechanisms may be envisaged. First, a redox-signaling element
generated within the lipid bilayer may stereospecifically interact with
a transmembrane or periplasmic segment of ArcB. In such a case, a
drastic change in amino acid sequence should disrupt signal
recognition. Second, the transmembrane region may simply serve as a
mechanical anchor to ensure proximity of the rest of ArcB to the
cytoplasmic membrane for signal reception. Third, one or both of the TM
segments may play an entirely novel and unsuspected role in signal
sensing. Results from the TM replacement experiments would favor the
second or third model. An example of the second model is the Aer
protein, which acts as a sensor for aerotaxis. In that case, anchorage
of the protein to cytoplasmic membrane by the two TM segments is
thought to allow the bound flavin adenine dinucleotide (FAD) to detect
the redox state of the electron transport chains (4, 39).
There is no evidence, however, that a cytosolic domain of ArcB binds to
FAD. First, although everted vesicles containing ArcB catalyzed the
phosphorylation of ArcA, the addition of FAD did not stimulate the
reaction (18). Second, unlike the case of Aer
(4), extracts of cells containing abundant ArcB (specified
by a multicopy plasmid) did not exhibit a detectable absorption
spectrum that is characteristic of flavins (O. Kwon, unpublished data).
Eventual identification of the true signal and the characterization of
its mode of reception will likely require a combined biochemical,
physiological, and genetic approach and the development of rigorous in
vitro assays. In the meantime, the results of our structural probing
revealed an unexpected degree of robustness of apparent ArcB function
to wholesale substitutions in the transmembrane region.
This work was supported by U.S. Public Health Service Grant GM40993
from NIGMS of the National Institutes of Health.
| 1.
|
Arico, B.,
J. F. Miller,
C. Roy,
S. Stibitz,
D. Monack,
S. Falkow,
R. Gross, and R. Rappuoli.
1989.
Sequences required for expression of Bordetella pertussis virulence factors share homology with prokaryotic signal transduction proteins.
Proc. Natl. Acad. Sci. USA
86:6671-6675[Abstract/Free Full Text].
|
| 2.
|
Avetisyan, A. V.,
A. V. Bogachev,
R. A. Murtasina, and V. P. Skulachev.
1992.
Involvement of a d-type oxidase in the Na+-motive respiratory chain of Escherichia coli growing under low H+ conditions.
FEBS Lett.
306:199-202[CrossRef][Medline].
|
| 3.
|
Barany, F.
1985.
Single-stranded hexameric linkers: a system for in-phase insertion mutagenesis and protein engineering.
Gene
37:111-123[CrossRef][Medline].
|
| 4.
|
Bibikov, S. I.,
R. Biran,
K. E. Rudd, and J. S. Parkinson.
1997.
A signal transducer for aerotaxis in Escherichia coli.
J. Bacteriol.
179:4075-4079[Abstract/Free Full Text].
|
| 5.
|
Bogachev, A. V.,
R. A. Murtazina, and V. P. Skulachev.
1993.
Cytochrome d induction in Escherichia coli growing under unfavorable conditions.
FEBS Lett.
336:75-78[CrossRef][Medline].
|
| 6.
|
Boyd, D.,
C. Manoil, and J. Beckwith.
1987.
Determinants of membrane protein topology.
Proc. Natl. Acad. Sci. USA
84:8525-8529[Abstract/Free Full Text].
|
| 7.
|
Cotter, P. A.,
V. Chepuri,
R. B. Gennis, and R. P. Gunsalus.
1990.
Cytochrome o (cyoABCDE) and d (cydAB) oxidase gene expression in Escherichia coli is regulated by oxygen, pH, and the fnr gene product.
J. Bacteriol.
172:6333-6338[Abstract/Free Full Text].
|
| 8.
|
Cotter, P. A.,
S. B. Melville,
J. A. Albrecht, and R. P. Gunsalus.
1997.
Aerobic regulation of cytochrome d oxidase (cydAB) operon expression in Escherichia coli: roles of Fnr and ArcA in repression and activation.
Mol. Microbiol.
25:605-615[CrossRef][Medline].
|
| 9.
|
Dong, J.-M.,
J. S. Taylor,
D. J. Latour,
S. Iuchi, and E. C. C. Lin.
1993.
Three overlapping lct genes involved in L-lactate utilization by Escherichia coli.
J. Bacteriol.
175:6671-6678[Abstract/Free Full Text].
|
| 10.
|
Doty, S. L.,
M. C. Yu,
J. I. Lundin,
J. Heath, and E. W. Nester.
1996.
Mutational analysis of the input domain of the VirA protein of Agrobacterium tumefaciens.
J. Bacteriol.
178:961-970[Abstract/Free Full Text].
|
| 11.
|
Fu, H.-A.,
S. Iuchi, and E. C. C. Lin.
1991.
The requirement of ArcA and Fnr for peak expression of the cyd operon in Escherichia coli under microaerobic conditions.
Mol. Gen. Genet.
226:209-213[CrossRef][Medline].
|
| 12.
|
Georgellis, D.,
O. Kwon,
P. De Wulf, and E. C. C. Lin.
1998.
Signal decay through a reverse phosphorelay in the Arc two-component signal transduction system.
J. Biol. Chem.
273:32864-32869[Abstract/Free Full Text].
|
| 13.
|
Georgellis, D.,
O. Kwon, and E. C. C. Lin.
1999.
Amplification of signaling activity of the Arc two-component system of Escherichia coli by anaerobic metabolites: an in vitro study with different protein modules.
J. Biol. Chem.
274:35950-35954[Abstract/Free Full Text].
|
| 14.
|
Georgellis, D.,
A. S. Lynch, and E. C. C. Lin.
1997.
In vitro phosphorylation study of the Arc two-component signal transduction system of Escherichia coli.
J. Bacteriol.
179:5429-5435[Abstract/Free Full Text].
|
| 15.
|
Hoch, J. A., and T. J. Silhavy (ed.).
1995.
Two-component signal transduction.
American Society for Microbiology, Washington, D.C.
|
| 16.
|
Hrabak, E. M., and D. K. Willis.
1992.
The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators.
J. Bacteriol.
174:3011-3020[Abstract/Free Full Text].
|
| 17.
|
Ishige, K.,
S. Nagasawa,
S.-I. Tokishita, and T. Mizuno.
1994.
A novel device of bacterial signal transducers.
EMBO J.
13:5195-5202[Medline].
|
| 18.
|
Iuchi, S.
1993.
Phosphorylation/dephosphorylation of the receiver module at the conserved aspartate residue controls transphosphorylation activity of histidine kinase in sensor protein ArcB of Escherichia coli.
J. Biol. Chem.
263:23972-23980.
|
| 19.
|
Iuchi, S.,
A. Aristarkhov,
J.-M. Dong,
J. S. Taylor, and E. C. C. Lin.
1994.
Effects of nitrate respiration on expression of the Arc-controlled operons encoding succinate dehydrogenase and flavin-linked L-lactate dehydrogenase.
J. Bacteriol.
176:1695-1701[Abstract/Free Full Text].
|
| 20.
|
Iuchi, S.,
D. C. Cameron, and E. C. C. Lin.
1989.
A second global regulator gene (arcB) mediating repression of enzymes in aerobic pathways of Escherichia coli.
J. Bacteriol.
171:868-873[Abstract/Free Full Text].
|
| 21.
|
Iuchi, S.,
V. Chepuri,
H.-A. Fu,
R. B. Gennis, and E. C. C. Lin.
1990.
Requirement for terminal cytochromes in generation of the aerobic signal for the arc regulatory system in Escherichia coli: study utilizing deletions and lac fusions of cyo and cyd.
J. Bacteriol.
172:6020-6025[Abstract/Free Full Text].
|
| 22.
|
Iuchi, S., and E. C. C. Lin.
1988.
arcA (dye), a global regulatory gene in Escherichia coli mediating repression of enzymes in aerobic pathways.
Proc. Natl. Acad. Sci. USA
85:1888-1892[Abstract/Free Full Text].
|
| 23.
|
Iuchi, S., and E. C. C. Lin.
1992.
Mutational analysis of signal transduction by ArcB: a membrane sensor protein for anaerobic expression of operons involved in the central aerobic pathways in Escherichia coli.
J. Bacteriol.
174:3972-3980[Abstract/Free Full Text].
|
| 24.
|
Iuchi, S.,
Z. Matsuda,
T. Fujiwara, and E. C. C. Lin.
1990.
The arcB gene of Escherichia coli encodes a sensor-regulator protein for anaerobic repression of the arc modulon.
Mol. Microbiol.
4:715-727[CrossRef][Medline].
|
| 25.
|
Jourlin, C.,
M. Ansaldi, and V. Méjean.
1997.
Transphosphorylation of the TorR response regulator requires the three phosphorylation sites of the TorS sensor in Escherichia coli.
J. Mol. Biol.
267:770-777[CrossRef][Medline].
|
| 26.
|
Kaspar, S.,
R. Perozzo,
S. Reinelt,
M. Meyer,
K. Pfister,
L. Scapozza, and M. Bott.
1999.
The periplasmic domain of the histidine autokinase CitA functions as a highly specific citrate receptor.
Mol. Microbiol.
33:858-872[CrossRef][Medline].
|
| 27.
|
Kato, M.,
T. Mizuno,
T. Shimizu, and T. Hakoshima.
1997.
Insights into multistep phosphorelay from the crystal structure of the C-terminal HPt domain of ArcB.
Cell
88:717-723[CrossRef][Medline].
|
| 28.
|
Kwon, O.,
M. E. S. Hudspeth, and R. Meganathan.
1996.
Anaerobic biosynthesis of enterobactin in Escherichia coli: regulation of entC gene expression and evidence against its involvement in menaquinone (vitamin K2) biosynthesis.
J. Bacteriol.
178:3252-3259[Abstract/Free Full Text].
|
| 29.
|
Kyte, J., and R. F. Doolittle.
1982.
A simple method for displaying the hydropathic character of a protein.
J. Mol. Biol.
154:367-382.
|
| 30.
|
Lynch, A. S., and E. C. C. Lin.
1996.
Responses to molecular oxygen, p. 1526-1538.
In
F. C. Neidhardt, R. Curtiss III, J. L. Ingraham, E. C. C. Lin, K. B. Low, B. Magasanik, W. S. Reznikoff, M. Riley, M. Schaechter, and H. E. Umbarger (ed.), Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed. American Society for Microbiology, Washington, D.C.
|
| 31.
|
Lynch, A. S., and E. C. C. Lin.
1996.
Transcriptional control mediated by the ArcA two-component response regulator protein of Escherichia coli: characterization of DNA binding at target promoters.
J. Bacteriol.
178:6238-6249[Abstract/Free Full Text].
|
| 32.
|
Manoil, C., and J. Beckwith.
1986.
A genetic approach to analyzing membrane protein topology.
Science
233:1403-1408[Abstract/Free Full Text].
|
| 33.
|
Miller, J. F.,
S. A. Johnson,
W. J. Black,
D. T. Beattie,
J. J. Mekalanos, and S. Falkow.
1992.
Constitutive sensory transduction mutations in the Bordetella pertussis bvgS gene.
J. Bacteriol.
174:970-979[Abstract/Free Full Text].
|
| 34.
|
Mowbray, S. L., and J. D. E. Koshland.
1990.
Mutations in the aspartate receptor of Escherichia coli which affect aspartate binding.
J. Biol. Chem.
265:15638-15643[Abstract/Free Full Text].
|
| 35.
|
Nagasawa, S.,
S. Tokishita,
H. Aiba, and T. Mizuno.
1992.
A novel sensor-regulator protein that belongs to the homologous family of signal-transduction proteins involved in adaptive responses in Escherichia coli.
Mol. Microbiol.
6:799-807[Medline].
|
| 36.
|
Oden, K. L.,
L. C. Deveaux,
C. R. Vibat,
J. E. Cronan, Jr., and R. B. Gennis.
1990.
Genomic replacement in Escherichia coli K-12 using covalently closed circular plasmid DNA.
Gene
30:29-36.
|
| 37.
|
Parkinson, J. S., and E. C. Kofoid.
1992.
Communication modules in bacterial signaling proteins.
Annu. Rev. Genet.
26:71-112[CrossRef][Medline].
|
| 38.
|
Reams, S. G.,
N. Lee,
F. Mat-Jan, and D. Clark.
1997.
Effect of chelating agents and respiratory inhibitors on regulation of the cadA gene in Escherichia coli.
Arch. Microbiol.
167:209-216[CrossRef][Medline].
|
| 39.
|
Rebbapragdala, A.,
M. S. Johnson,
G. P. Harding,
A. J. Zuccarilli,
H. M. Fletcher,
I. B. Zhulin, and B. L. Taylor.
1997.
The Aer protein and the serine chemoreceptor Tsr independently sense intracellular energy levels and transduce oxygen, redox, and energy signals for Escherichia coli behavior.
Proc. Natl. Acad. Sci. USA
94:10541-10546[Abstract/Free Full Text].
|
| 40.
|
Rost, B.,
P. Fariselli, and R. Casadio.
1996.
Topology prediction for helical transmembrane proteins at 86% accuracy.
Protein Sci.
5:1704-1718[Abstract].
|
| 41.
|
Sarkar, G., and S. S. Sommer.
1990.
The "megaprimer" method of site-directed mutagenesis.
BioTechniques
8:404-407[Medline].
|
| 42.
|
Simons, R. W.,
F. Houman, and N. Kleckner.
1987.
Improved single and multicopy lac-based cloning vectors for protein and operon fusions.
Gene
53:85-96[CrossRef][Medline].
|
| 43.
|
Spiro, S., and J. R. Guest.
1987.
Activation of the lac operon of Escherichia coli by a mutant FNR protein.
Mol. Microbiol.
1:53-58[CrossRef][Medline].
|
| 44.
|
Stevens, A. M.,
J. M. Sanders,
N. B. Shoemaker, and A. A. Salyers.
1992.
Genes involved in production of plasmid-like forms by a Bacteroides conjugal chromosomal element share amino acid homology with two-component regulatory systems.
J. Bacteriol.
174:2935-2942[Abstract/Free Full Text].
|
| 45.
|
Tapia, M. I.,
M. Mourez,
M. Hofnung, and E. Dassa.
1999.
Structure-function study of MalF protein by random mutagenesis.
J. Bacteriol.
181:2267-2272[Abstract/Free Full Text].
|
| 46.
|
Taylor, B. L., and I. B. Zhulin.
1999.
PAS domains: internal sensors of oxygen, redox potential, and light.
Microbiol. Mol. Biol. Rev.
63:479-506[Abstract/Free Full Text].
|
| 47.
|
Tokishita, S.,
A. Kojima, and T. Mizuno.
1991.
Transmembrane signal transduction and osmoregulation in Escherichia coli: functional importance of the periplasmic domain of the membrane-located protein kinase, EnvZ.
J. Biol. Chem.
266:6780-6785[Abstract/Free Full Text].
|
| 48.
|
Tsuzuki, M.,
K. Ishege, and T. Mizuno.
1995.
Phosphotransfer circuitry of the putative multi-signal transducer, ArcB, of Escherichia coli: in vitro studies with mutants.
Mol. Microbiol.
18:953-962[CrossRef][Medline].
|
| 49.
|
Utsumi, R.,
S. Katayama,
M. Taniguchi,
T. Horie,
M. Ikeda,
S. Igaki,
H. Nakagawa,
A. Miwa,
H. Tanabe, and M. Noda.
1994.
Newly identified genes involved in the signal transduction of Escherichia coli K-12.
Gene
140:73-77[CrossRef][Medline].
|
| 50.
|
Way, J. C.,
M. A. Davis,
D. Morisato,
D. E. Roberts, and N. Kleckner.
1984.
New Tn10 derivatives for transposon mutagenesis and for construction of lacZ operon fusions by transposition.
Gene
32:369-379[CrossRef][Medline].
|
![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
Top
Abstract
Text
