scholarly journals A Redox-Responsive Pathway for Aerobic Regulation of Photosynthesis Gene Expression in Rhodobacter sphaeroides 2.4.1

1998 ◽  
Vol 180 (16) ◽  
pp. 4044-4050 ◽  
Author(s):  
James P. O’Gara ◽  
Jesus M. Eraso ◽  
Samuel Kaplan
Keyword(s):  
Gene Expression ◽  
Cytochrome Oxidase ◽  
Rhodobacter Sphaeroides ◽  
Double Mutant ◽  
Signal Transduction Pathway ◽  
Growth Conditions ◽  
Two Component ◽  
Activation System ◽  
Mutant Strains ◽  
Photosynthesis Gene

ABSTRACT To further understand the proposed signal transduction pathway involving the presumed redox proteins RdxBH andcbb 3 cytochrome oxidase in Rhodobacter sphaeroides 2.4.1, a series of mutants lacking components of both the Prr two-component activation system and thecbb 3-type cytochrome oxidase or RdxBH were constructed. We report that under highly aerobic conditions, aberrant photosynthesis gene expression and spectral complex formation typical of cbb 3- or RdxBH-deficient mutants were no longer observed when either prrA (encoding the response regulator of the Prr system) or prrB (encoding the presumed sensor kinase) was also deleted. These double-mutant strains are phenotypically identical to single-mutant PrrA and PrrB strains, suggesting that the signal(s) originating from thecbb 3 terminal oxidase affects downstreampuc and puf operon expression by acting exclusively through the Prr system. When the same double-mutant strains were examined under anaerobic dark dimethyl sulfoxide growth conditions, photosynthesis gene expression was obligatorily linked to the two-component activation system. However, photosynthesis gene expression under the same growth conditions was significantly higher in the cbb 3 mutant strain when compared to that in the wild type. Similarly, under anaerobic photosynthetic conditions the high levels of the oxidized carotenoid, spheroidenone, which accumulate in cbb 3-deficient mutants were nearly restored to normal in a PrrB− CcoP− double mutant. This observation, together with previously published results, suggests that the regulation of the CrtA-catalyzed reaction possesses both transcriptional and posttranscriptional regulatory effectors. We propose that the cbb 3 cytochrome oxidase, which by definition can interact with external oxygen, serves to control the activity of the Prr two-component activation system under both aerobic and anaerobic conditions. Although independent from thecbb 3 oxidase, the RdxBH proteins are also required for normal functioning of the Prr two-component activation system and are therefore believed to lie between thecbb 3 oxidase in this oxygen-sensing, redox signaling pathway and the Prr activation system.

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 Interdependent Expression of the ccoNOQP-rdxBHIS Loci in Rhodobacter sphaeroides 2.4.1

2002 ◽  
Vol 184 (19) ◽  
pp. 5330-5338 ◽  
Author(s):  
Jung Hyeob Roh ◽  
Samuel Kaplan
Keyword(s):  
Gene Expression ◽  
Gene Cluster ◽  
Rhodobacter Sphaeroides ◽  
Northern Blot Analysis ◽  
Signal Transduction Pathway ◽  
Reverse Transcription Pcr ◽  
Microaerobic Conditions ◽  
Fusion Analysis ◽  
Transcriptional Start Sites ◽  
Photosynthesis Gene

ABSTRACT The rdxBHIS gene cluster of Rhodobacter sphaeroides 2.4.1, located downstream of the ccoNOQP operon encoding the cbb 3 cytochrome c oxidase, is required for the posttranscriptional modification of the cbb 3 cytochrome c oxidase. The cbb 3 cytochrome c oxidase is the main terminal oxidase under microaerobic conditions, as well as a component of the signal transduction pathway controlling photosynthesis gene expression. Because of the intimate functional and positional relationships of the ccoNOQP operon and the rdxBHIS gene cluster, we have examined the transcriptional activities of this DNA region in order to understand their expression and regulation. Northern blot analysis and reverse transcription-PCR, together with earlier complementation analysis, suggested that the ccoNOQP-rdxBHIS cluster is transcribed as ccoNOQP-, ccoNOQP-rdxBH-, rdxBH-, and rdxIS-specific transcripts. Multiple transcriptional start sites have been identified by primer extension analyses: five for ccoN, four for rdxB, and one for rdxI. Transcription from P1N of ccoN and P1B of rdxB is dependent on the presence of FnrL. LacZ fusion analysis support the above-described studies, especially the importance of FnrL. Expression of the cco-rdx cluster is closely related to photosynthesis gene expression, suggesting that transcript stoichiometry and presumably the stoichiometry of the gene products are critical factors in controlling photosynthesis gene expression.

scholarly journals Effect of Overexpressing rsmA from Pseudomonas aeruginosa on Virulence of Select Phytotoxin-Producing Strains of P. syringae

2012 ◽  
Vol 102 (6) ◽  
pp. 575-587 ◽  
Author(s):  
Hye Suk Kong ◽  
Daniel P. Roberts ◽  
Cheryl D. Patterson ◽  
Sarah A. Kuehne ◽  
Stephan Heeb ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Signal Transduction Pathway ◽  
Leaf Tissue ◽  
Transcriptional Regulators ◽  
Growth Conditions ◽  
Transduction Pathway ◽  
Two Component System ◽  
Empty Vector ◽  
Alginate Production ◽  
Two Component

The GacS/GacA two-component system functions mechanistically in conjunction with global post-transcriptional regulators of the RsmA family to allow pseudomonads and other bacteria to adapt to changing environmental stimuli. Analysis of this Gac/Rsm signal transduction pathway in phytotoxin-producing pathovars of Pseudmonas syringae is incomplete, particularly with regard to rsmA. Our approach in studying it was to overexpress rsmA in P. syringae strains through introduction of pSK61, a plasmid constitutively expressing this gene. Disease and colonization of plant leaf tissue were consistently diminished in all P. syringae strains tested (pv. phaseolicola NPS3121, pv. syringae B728a, and BR2R) when harboring pSK61 relative to these isolates harboring the empty vector pME6031. Phaseolotoxin, syringomycin, and tabtoxin were not produced in any of these strains when transformed with pSK61. Production of protease and pyoverdin as well as swarming were also diminished in all of these strains when harboring pSK61. In contrast, alginate production, biofilm formation, and the hypersensitive response were diminished in some but not all of these isolates under the same growth conditions. These results indicate that rsmA is consistently important in the overarching phenotypes disease and endophtyic colonization but that its role varies with pathovar in certain underpinning phenotypes in the phytotoxin-producing strains of P. syringae.

scholarly journals The CtrA Regulon of Rhodobacter sphaeroides Favors Adaptation to a Particular Lifestyle

2020 ◽  
Vol 202 (7) ◽  
Author(s):  
José Hernández-Valle ◽  
Alejandro Sanchez-Flores ◽  
Sebastian Poggio ◽  
Georges Dreyfus ◽  
Laura Camarena
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Stress Responses ◽  
Transcriptome Sequencing ◽  
Growth Conditions ◽  
Fine Tuning ◽  
Rna Seq ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component

ABSTRACT Activation of the two-component system formed by CckA, ChpT, and CtrA (kinase, phosphotransferase, and response regulator, respectively) in Rhodobacter sphaeroides does not occur under the growth conditions commonly used in the laboratory. However, it is possible to isolate a gain-of-function mutant in CckA that turns the system on. Using massive parallel transcriptome sequencing (RNA-seq), we identified 321 genes that are differentially regulated by CtrA. From these genes, 239 were positively controlled and 82 were negatively regulated. Genes encoding the Fla2 polar flagella and gas vesicle proteins are strongly activated by CtrA. Genes involved in stress responses as well as several transcriptional factors are also positively controlled, whereas the photosynthetic and CO2 fixation genes are repressed. Potential CtrA-binding sites were bioinformatically identified, leading to the proposal that at least 81 genes comprise the direct regulon. Based on our results, we ponder that the transcriptional response orchestrated by CtrA enables a lifestyle in which R. sphaeroides will effectively populate the surface layer of a water body enabled by gas vesicles and will remain responsive to chemotactic stimuli using the chemosensoring system that controls the Fla2 flagellum. Simultaneously, fine-tuning of photosynthesis and stress responses will reduce the damage caused by heat and high light intensity in this water stratum. In summary, in this bacterium CtrA has evolved to control physiological responses that allow its adaptation to a particular lifestyle instead of controlling the cell cycle as occurs in other species. IMPORTANCE Cell motility in Alphaproteobacteria is frequently controlled by the CckA, ChpT, and CtrA two-component system. Under the growth conditions commonly used in the laboratory, ctrA is transcriptionally inactive in Rhodobacter sphaeroides, and motility depends on the Fla1 flagellar system that was acquired by a horizontal transfer event. Likely, the incorporation of this flagellar system released CtrA from the strong selective pressure of being the main motility regulator, allowing this two-component system to specialize and respond to some specific conditions. Identifying the genes that are directly regulated by CtrA could help us understand the conditions in which the products of this regulon are required. Massive parallel transcriptome sequencing (RNA-seq) revealed that CtrA orchestrates an adaptive response that contributes to the colonization of a particular environmental niche.

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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