scholarly journals prrA, a putative response regulator involved in oxygen regulation of photosynthesis gene expression in Rhodobacter sphaeroides.

1994 ◽  
Vol 176 (1) ◽  
pp. 32-43 ◽  
Author(s):  
J M Eraso ◽  
S Kaplan
Keyword(s):  
Gene Expression ◽  
Rhodobacter Sphaeroides ◽  
Response Regulator ◽  
Oxygen Regulation ◽  
Photosynthesis Gene ◽  
Regulation Of Photosynthesis

scholarly journals Hierarchical Regulation of Photosynthesis Gene Expression by the Oxygen-Responsive PrrBA and AppA-PpsR Systems of Rhodobacter sphaeroides

2008 ◽  
Vol 190 (24) ◽  
pp. 8106-8114 ◽  
Author(s):  
Larissa Gomelsky ◽  
Oleg V. Moskvin ◽  
Rachel A. Stenzel ◽  
Denise F. Jones ◽  
Timothy J. Donohue ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rhodobacter Sphaeroides ◽  
Response Regulator ◽  
Photosynthetic Apparatus ◽  
Regulatory System ◽  
Structural Proteins ◽  
Gene Encoding ◽  
Genes Encoding ◽  
Photosynthetic Complexes ◽  
Photosynthesis Gene

ABSTRACT In the facultatively phototrophic proteobacterium Rhodobacter sphaeroides, formation of the photosynthetic apparatus is oxygen dependent. When oxygen tension decreases, the response regulator PrrA of the global two-component PrrBA system is believed to directly activate transcription of the puf, puh, and puc operons, encoding structural proteins of the photosynthetic complexes, and to indirectly upregulate the photopigment biosynthesis genes bch and crt. Decreased oxygen also results in inactivation of the photosynthesis-specific repressor PpsR, bringing about derepression of the puc, bch, and crt operons. We uncovered a hierarchical relationship between these two regulatory systems, earlier thought to function independently. We also more accurately assessed the spectrum of gene targets of the PrrBA system. First, expression of the appA gene, encoding the PpsR antirepressor, is PrrA dependent, which establishes one level of hierarchical dominance of the PrrBA system over AppA-PpsR. Second, restoration of the appA transcript to the wild-type level is insufficient for rescuing phototrophic growth impairment of the prrA mutant, whereas inactivation of ppsR is sufficient. This suggests that in addition to controlling appA transcription, PrrA affects the activity of the AppA-PpsR system via an as yet unidentified mechanism(s). Third, PrrA directly activates several bch and crt genes, traditionally considered to be the PpsR targets. Therefore, in R. sphaeroides, the global PrrBA system regulates photosynthesis gene expression (i) by rigorous control over the photosynthesis-specific AppA-PpsR regulatory system and (ii) by extensive direct transcription activation of genes encoding structural proteins of photosynthetic complexes as well as genes encoding photopigment biosynthesis enzymes.

scholarly journals Genetic and Phenotypic Analyses of therdx Locus of Rhodobacter sphaeroides2.4.1

2000 ◽  
Vol 182 (12) ◽  
pp. 3475-3481 ◽  
Author(s):  
Jung Hyeob Roh ◽  
Samuel Kaplan
Keyword(s):  
Gene Expression ◽  
Rhodobacter Sphaeroides ◽  
Redox Protein ◽  
Deletion Mutations ◽  
Metal Transporter ◽  
New Class ◽  
Mutant Strains ◽  
Membrane Bound ◽  
Photosynthesis Gene

ABSTRACT Previously, we reported that rdxB, encoding a likely membrane-bound two [4Fe-4S]-containing center, is involved in the aerobic regulation of photosystem gene expression in Rhodobacter sphaeroides 2.4.1. To further investigate the role ofrdxB as well as other genes of the rdxBHISoperon on photosystem gene expression, we constructed a series of nonpolar, in-frame deletion mutations in each of the rdxgenes. Using both puc and puf operonlacZ fusions to monitor photosystem gene expression, under aerobic conditions, in each of the mutant strains revealed significant increased photosynthesis gene expression. In the case of mutations in either rdxH, rdxI, or rdxS, the aerobic induction of photosystem gene expression is believed to be indirect by virtue of a posttranscriptional effect oncbb 3 cytochrome oxidase structure and integrity. For RdxB, we suggest that this redox protein has a more direct effect on photosystem gene expression by virtue of its interaction with the cbb 3 oxidase. An associated phenotype, involving the enhanced conversion of the carotenoid spheroidene to spheroidenone, is also observed in the RdxB, -H, -I, and -S mutant strains. This phenotype is also suggested to be the result of the role of the rdxBHIS locus incbb 3 oxidase activity and/or structure. RdxI is suggested to be a new class of metal transporter of the CPx-type ATPases.

scholarly journals Differential Expression of the CO2 Fixation Operons of Rhodobacter sphaeroides by the Prr/Reg Two-Component System during Chemoautotrophic Growth

2002 ◽  
Vol 184 (23) ◽  
pp. 6654-6664 ◽  
Author(s):  
Janet L. Gibson ◽  
James M. Dubbs ◽  
F. Robert Tabita
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Cytochrome Oxidase ◽  
Rhodobacter Sphaeroides ◽  
Rhodobacter Capsulatus ◽  
Response Regulator ◽  
Signal Transduction Pathway ◽  
Pentose Phosphate ◽  
Bisphosphate Carboxylase

ABSTRACT In Rhodobacter sphaeroides, the two cbb operons encoding duplicated Calvin-Benson Bassham (CBB) CO2 fixation reductive pentose phosphate cycle structural genes are differentially controlled. In attempts to define the molecular basis for the differential regulation, the effects of mutations in genes encoding a subunit of Cbb3 cytochrome oxidase, ccoP, and a global response regulator, prrA (regA), were characterized with respect to CO2 fixation (cbb) gene expression by using translational lac fusions to the R. sphaeroides cbb I and cbbII promoters. Inactivation of the ccoP gene resulted in derepression of both promoters during chemoheterotophic growth, where cbb expression is normally repressed; expression was also enhanced over normal levels during phototrophic growth. The prrA mutation effected reduced expression of cbbI and cbbII promoters during chemoheterotrophic growth, whereas intermediate levels of expression were observed in a double ccoP prrA mutant. PrrA and ccoP1 prrA strains cannot grow phototrophically, so it is impossible to examine cbb expression in these backgrounds under this growth mode. In this study, however, we found that PrrA mutants of R. sphaeroides were capable of chemoautotrophic growth, allowing, for the first time, an opportunity to directly examine the requirement of PrrA for cbb gene expression in vivo under growth conditions where the CBB cycle and CO2 fixation are required. Expression from the cbbII promoter was severely reduced in the PrrA mutants during chemoautotrophic growth, whereas cbbI expression was either unaffected or enhanced. Mutations in ccoQ had no effect on expression from either promoter. These observations suggest that the Prr signal transduction pathway is not always directly linked to Cbb3 cytochrome oxidase activity, at least with respect to cbb gene expression. In addition, lac fusions containing various lengths of the cbbI promoter demonstrated distinct sequences involved in positive regulation during photoautotrophic versus chemoautotrophic growth, suggesting that different regulatory proteins may be involved. In Rhodobacter capsulatus, ribulose 1,5-bisphosphate carboxylase-oxygenase (RubisCO) expression was not affected by cco mutations during photoheterotrophic growth, suggesting that differences exist in signal transduction pathways regulating cbb genes in the related organisms.

scholarly journals The AppA and PpsR Proteins from Rhodobacter sphaeroides Can Establish a Redox-Dependent Signal Chain but Fail To Transmit Blue-Light Signals in Other Bacteria

2007 ◽  
Vol 189 (6) ◽  
pp. 2274-2282 ◽  
Author(s):  
Andreas Jäger ◽  
Stephan Braatsch ◽  
Kerstin Haberzettl ◽  
Sebastian Metz ◽  
Lisa Osterloh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Blue Light ◽  
Rhodobacter Sphaeroides ◽  
Rhodobacter Capsulatus ◽  
Paracoccus Denitrificans ◽  
Response Regulator ◽  
Bacterial Species ◽  
Protein Protein Interaction ◽  
Dependent Signal ◽  
Light Signals

ABSTRACT The AppA protein of Rhodobacter sphaeroides has the unique ability to sense and transmit redox and light signals. In response to decreasing oxygen tension, AppA antagonizes the transcriptional regulator PpsR, which represses the expression of photosynthesis genes, including the puc operon. This mechanism, which is based on direct protein-protein interaction, is prevented by blue-light absorption of the BLUF domain located in the N-terminal part of AppA. In order to test whether AppA and PpsR are sufficient to transmit redox and light signals, we expressed these proteins in three different bacterial species and monitored oxygen- and blue-light-dependent puc expression either directly or by using a luciferase-based reporter construct. The AppA/PpsR system could mediate redox-dependent gene expression in the alphaproteobacteria Rhodobacter capsulatus and Paracoccus denitrificans but not in the gammaproteobacterium Escherichia coli. Analysis of a prrA mutant strain of R. sphaeroides strongly suggests that light-dependent gene expression requires a balanced interplay of the AppA/PpsR system with the PrrA response regulator. Therefore, the AppA/PpsR system was unable to establish light signaling in other bacteria. Based on our data, we present a model for the interdependence of AppA/PpsR signaling and the PrrA transcriptional activator.

scholarly journals Dominant Role of the cbb3 Oxidase in Regulation of Photosynthesis Gene Expression through the PrrBA System in Rhodobacter sphaeroides 2.4.1

2007 ◽  
Vol 189 (15) ◽  
pp. 5617-5625 ◽  
Author(s):  
Yong-Jin Kim ◽  
In-Jeong Ko ◽  
Jin-Mok Lee ◽  
Ho-Young Kang ◽  
Young Min Kim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rhodobacter Sphaeroides ◽  
Transmembrane Domain ◽  
Dominant Role ◽  
Mutant Form ◽  
Two Component System ◽  
Signaling Function ◽  
Membrane Bound ◽  
Binding Sequence ◽  
Photosynthesis Gene

ABSTRACT In this study, the H303A mutant form of the cbb 3 oxidase (H303A oxidase), which has the H303A mutation in its catalytic subunit (CcoN), was purified from Rhodobacter sphaeroides. The H303A oxidase showed the same catalytic activity as did the wild-type form of the oxidase (WT oxidase). The heme contents of the mutant and WT forms of the cbb 3 oxidase were also comparable. However, the puf and puc operons, which are under the control of the PrrBA two-component system, were shown to be derepressed aerobically in the R. sphaeroides strain expressing the H303A oxidase. Since the strain harboring the H303A oxidase exhibited the same cytochrome c oxidase activity as the stain harboring the WT oxidase did, the aerobic derepression of photosynthesis gene expression observed in the H303A mutant appears to be the result of a defective signaling function of the H303A oxidase rather than reflecting any redox changes in the ubiquinone/ubiquinol pool. It was also demonstrated that ubiquinone inhibits not only the autokinase activity of full-length PrrB but also that of the truncated form of PrrB lacking its transmembrane domain, including the proposed quinone binding sequence. These results imply that the suggested ubiquinone binding site within the PrrB transmembrane domain is not necessary for the inhibition of PrrB kinase activity by ubiquinone. Instead, it is probable that signaling through H303 of the CcoN subunit of the cbb 3 oxidase is part of the pathway through which the cbb 3 oxidase affects the relative kinase/phosphatase activity of the membrane-bound PrrB.

scholarly journals The PpaA/AerR Regulators of Photosynthesis Gene Expression from Anoxygenic Phototrophic Proteobacteria Contain Heme-Binding SCHIC Domains

2010 ◽  
Vol 192 (19) ◽  
pp. 5253-5256 ◽  
Author(s):  
Oleg V. Moskvin ◽  
Marie-Alda Gilles-Gonzalez ◽  
Mark Gomelsky
Keyword(s):  
Gene Expression ◽  
Rhodobacter Sphaeroides ◽  
Binding Domain ◽  
Heme Binding ◽  
Domain Family ◽  
Sequence Identity ◽  
Photosynthesis Gene

ABSTRACT The SCHIC domain of the B12-binding domain family present in the Rhodobacter sphaeroides AppA protein binds heme and senses oxygen. Here we show that the predicted SCHIC domain PpaA/AerR regulators also bind heme and respond to oxygen in vitro, despite their low sequence identity with AppA.

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