Previous Article | Next Article 
Journal of Bacteriology, April 2000, p. 2253-2261, Vol. 182, No. 8
Department of Microbiology and Molecular
Genetics, University of Texas Medical School, Houston, Texas
77030,1 and Department of Microbiology
and Parasitology, University of Queensland, Brisbane, Queensland
4072, Australia2
Received 18 October 1999/Accepted 18 January 2000
The transcription factor PpsR from the facultative photoheterotroph
Rhodobacter sphaeroides is involved in repression of
photosystem gene expression under aerobic growth conditions. We have
isolated a number of spontaneous mutations as well as constructed
directed mutations and deletions in ppsR. Repressor
activities and the oligomeric state of the wild-type and mutant
proteins were assayed. Our results suggest that the wild-type
PpsR exists in cell extracts as a tetramer. Analysis of the PpsR
mutants confirmed that the carboxy-terminal region of PpsR (residues
400 to 464) is involved in DNA binding. The central region of the
protein (residues 150 to 400) was found to contain two PAS domains
(residues 161 to 259 and 279 to 367). PAS domains are ubiquitous
protein modules involved in sensory transduction as well as in
protein-protein interactions. All spontaneously isolated mutations,
which significantly impaired repressor activity and which mapped
outside the DNA binding region, were positioned in the PAS domains.
None of these, however, affected the overall oligomeric state.
This implies that the conformation of the PAS domains within the
tetramer is critical for repressor activity. Upstream of the first PAS
domain resides a putative glutamine-rich hinge (residues 127 to 136)
that connects the first PAS domain to the amino-terminal region
(residues 1 to 135). The role of the amino terminus of PpsR is not
obvious; however, extended deletions within this region abolish
repressor activity, thus suggesting that the amino terminus is
essential for structural integrity of the protein. We present a model
of the domain architecture of the PpsR protein according to which PpsR
is comprised of three regions: the carboxy terminus responsible for DNA
binding, the central region primarily involved in protein
oligomerization and possibly signal sensing, and the amino terminus of
unknown function. This model may prove useful for determining the
mode of PpsR action.
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Domain Structure, Oligomeric State, and Mutational Analysis
of PpsR, the Rhodobacter sphaeroides Repressor of
Photosystem Gene Expression
*
Corresponding author. Mailing address: Department of
Microbiology and Molecular Genetics, University of Texas Medical
School, 6431 Fannin St., Houston, TX 77030. Phone (713) 500-5502. Fax: (713) 500-5499. E-mail:
skaplan{at}utmmg.med.uth.tmc.edu.
Present address: Department of Molecular Biology, University of
Wyoming, Laramie, WY 82071.
Permanent address: Department of Biology, College of Natural
Sciences, Dong-A University, Pusan, South Korea.
Journal of Bacteriology, April 2000, p. 2253-2261, Vol. 182, No. 8
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Gomelsky, L., Moskvin, O. V., Stenzel, R. A., Jones, D. F., Donohue, T. J., Gomelsky, M.
(2008). Hierarchical Regulation of Photosynthesis Gene Expression by the Oxygen-Responsive PrrBA and AppA-PpsR Systems of Rhodobacter sphaeroides. J. Bacteriol.
190: 8106-8114
[Abstract] [Full Text] -
Bruscella, P., Eraso, J. M., Roh, J. H., Kaplan, S.
(2008). The Use of Chromatin Immunoprecipitation to Define PpsR Binding Activity in Rhodobacter sphaeroides 2.4.1. J. Bacteriol.
190: 6817-6828
[Abstract] [Full Text] -
Mao, L., Mackenzie, C., Roh, J. H., Eraso, J. M., Kaplan, S., Resat, H.
(2005). Combining microarray and genomic data to predict DNA binding motifs. Microbiology
151: 3197-3213
[Abstract] [Full Text] -
Moskvin, O. V., Gomelsky, L., Gomelsky, M.
(2005). Transcriptome Analysis of the Rhodobacter sphaeroides PpsR Regulon: PpsR as a Master Regulator of Photosystem Development. J. Bacteriol.
187: 2148-2156
[Abstract] [Full Text] -
Braatsch, S., Moskvin, O. V., Klug, G., Gomelsky, M.
(2004). Responses of the Rhodobacter sphaeroides Transcriptome to Blue Light under Semiaerobic Conditions. J. Bacteriol.
186: 7726-7735
[Abstract] [Full Text] -
Jaubert, M., Zappa, S., Fardoux, J., Adriano, J.-M., Hannibal, L., Elsen, S., Lavergne, J., Vermeglio, A., Giraud, E., Pignol, D.
(2004). Light and Redox Control of Photosynthesis Gene Expression in Bradyrhizobium: DUAL ROLES OF TWO PpsR. J. Biol. Chem.
279: 44407-44416
[Abstract] [Full Text] -
Roh, J. H., Smith, W. E., Kaplan, S.
(2004). Effects of Oxygen and Light Intensity on Transcriptome Expression in Rhodobacter sphaeroides 2.4.1: REDOX ACTIVE GENE EXPRESSION PROFILE. J. Biol. Chem.
279: 9146-9155
[Abstract] [Full Text] -
Cho, S.-H., Youn, S.-H., Lee, S.-R., Yim, H.-S., Kang, S.-O.
(2004). Redox property and regulation of PpsR, a transcriptional repressor of photosystem gene expression in Rhodobacter sphaeroides. Microbiology
150: 697-706
[Abstract] [Full Text] -
Gomelsky, L., Sram, J., Moskvin, O. V., Horne, I. M., Dodd, H. N., Pemberton, J. M., McEwan, A. G., Kaplan, S., Gomelsky, M.
(2003). Identification and in vivo characterization of PpaA, a regulator of photosystem formation in Rhodobacter sphaeroides. Microbiology
149: 377-388
[Abstract] [Full Text] -
Zeng, X., Kaplan, S.
(2001). TspO as a Modulator of the Repressor/Antirepressor (PpsR/AppA) Regulatory System in Rhodobacter sphaeroides 2.4.1. J. Bacteriol.
183: 6355-6364
[Abstract] [Full Text]
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»