Electron transport-dependent taxis in Rhodobacter sphaeroides

Gauden, David E.; Armitage, Judith P.

doi:10.1128/jb.177.20.5853-5859.1995

Cited by 44 publications

(50 citation statements)

References 38 publications

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“…These results have led to the current dogma that the scotophobic response is mediated by the perception of a sudden decrease in the rate of photosynthesis rather than by light absorption through a specific photoreceptor. The mechanism of measuring a reduction in the efficiency of photosynthesis appears to involve monitoring alterations in the rate of photosynthesis-driven electron transport (10,14).The use of the bacterium Rhodospirillum centenum as a model organism for studying bacterial photoperception is particularly appealing since it is known to exhibit two distinctive photosensory processes (29,30). When grown in liquid medium, R. centenum cells, which are motile by means of a single polar flagellum, exhibit a typical scotophobic response.…”

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Analysis of a chemotaxis operon from Rhodospirillum centenum

Jiang

Bauer

1997

J Bacteriol

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A chemotaxis gene cluster from the photosynthetic bacterium Rhodospirillum centenum has been cloned, sequenced, and analyzed for the control of transcription during swimmer-to-swarm cell differentiation. The first gene of the operon (cheAY) codes for a large 108-kDa polypeptide with an amino-terminal domain that is homologous to CheA and a carboxyl terminus that is homologous to CheY. cheAY is followed by cheW, an additional homolog of cheY, cheB, and cheR. Sequence analysis indicated that all of the che genes are tightly compacted with the same transcriptional polarity, suggesting that they are organized in an operon. Cotranscription of the che genes was confirmed by demonstrating through Western blot analysis that insertion of a polar spectinomycin resistance gene in cheAY results in loss of cheR expression. The promoter for the che operon was mapped by primer extension analysis as well as by the construction of promoter reporter plasmids that include several deletion intervals. This analysis indicated that the R. centenum che operon utilizes two promoters; one exhibits a 70 -like sequence motif, and the other exhibits a 54 -like motif. Expression of the che operon is shown to be relatively constant for swimmer cells which contain a single flagellum and for swarm cells that contain multiple lateral flagella.More than a century ago, Engelmann (7) observed that when purple sulfur photosynthetic bacteria of the genus Chromatium were illuminated with a broad spectrum of light, the cells accumulated at wavelengths that corresponded to the in vivo absorption peaks of the cells. A more accurate description of this phenomenon is that when smooth-swimming cells migrate into a dark region (or into regions of the spectrum where wavelengths are not absorbed by photopigments), they either tumble or reverse the direction of movement, depending on the species. The phenomenon has been termed a scotophobic (fear of darkness) response since the cells exhibit an aversion to darkness rather than a specific affinity for light (12,29). Since a reduction in light intensity causes a tumbling/reversal response, the mechanism of moving through an increasing gradient of light intensity appears to involve a directed "random walk" such that the length of smooth swimming is longer when cells are going up a light gradient than when they are going down. Superficially, this process is not unlike the wellcharacterized bacterial "trial-and-error" walking up a chemical gradient that is mediated by chemoreceptors and the Che protein phosphorylation cascade (2, 40).The mechanism whereby a reduction in light intensity causes a tumbling/reversal response is still unclear. However, recent work has revealed that a functioning photosynthetic apparatus is required for photosensory perception (3). In addition, chemical inhibition of electron carrier components such as the cytochrome bc 1 complex, are incapable of light perception (4). These results have led to the current dogma that the scotophobic response is mediated by the perception of a sudden decre...

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Analysis of a chemotaxis operon from Rhodospirillum centenum

Jiang

Bauer

1997

J Bacteriol

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“…A postulated aerotaxis-transducing protein responds to the increase in electron transport͞proton motive force and initiates a signal for the behavioral response to oxygen (3)(4)(5)(6). Chemicals other than oxygen that stimulate electron transport also elicit an aerotaxis-like behavioral response in bacteria (5,7,8). The aerotaxis transducer may mediate other types of bacterial behavior, such as the newly described taxis to a preferred redox potential (9) and energy taxis to carbon sources, such as glycerol (10) or proline (11).…”

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The Aer protein and the serine chemoreceptor Tsr independently sense intracellular energy levels and transduce oxygen, redox, and energy signals for Escherichia coli behavior

Rebbapragada

Johnson

Harding

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

258

350

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We identified a protein, Aer, as a signal transducer that senses intracellular energy levels rather than the external environment and that transduces signals for aerotaxis (taxis to oxygen) and other energy-dependent behavioral responses in Escherichia coli. Domains in Aer are similar to the signaling domain in chemotaxis receptors and the putative oxygen-sensing domain of some transcriptional activators. A putative FAD-binding site in the N-terminal domain of Aer shares a consensus sequence with the NifL, Bat, and Wc-1 signal-transducing proteins that regulate gene expression in response to redox changes, oxygen, and blue light, respectively. A double mutant deficient in aer and tsr, which codes for the serine chemoreceptor, was negative for aerotaxis, redox taxis, and glycerol taxis, each of which requires the proton motive force and͞or electron transport system for signaling. We propose that Aer and Tsr sense the proton motive force or cellular redox state and thereby integrate diverse signals that guide E. coli to environments where maximal energy is available for growth.

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“…An alternative method for assessing the ability of R. sphaeroides strains to utilize a particular respiratory substrate is to assess their ability to show taxis towards the substrate. Chemotaxis towards a particular electron acceptor in R. sphaeroides is directly dependent on the ability to respire using that compound as an electron acceptor (Gauden & Armitage, 1995). If NnrS is involved in nitrogen oxide metabolism, it is possible that NnrS-deficient mutants exhibit changes in taxis towards nitrogen oxides that are not discernible using liquid cultures.…”

Section: Effect Of Nnrs Inactivation On Chemotaxis To Nitritementioning

confidence: 99%

“…Taxis assays were similar to previously described R. sphaeroides taxis assays (Gauden & Armitage, 1995). Cells for taxis assays were grown microaerobically in medium unamended with nitrate.…”

Section: Methodsmentioning

confidence: 99%

Characterization of a member of the NnrR regulon in Rhodobacter sphaeroides 2.4.3 encoding a haem–copper protein The GenBank accession number for nnrS is U62403.

et al. 2002

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Upstream of the nor and nnrR cluster in Rhodobacter sphaeroides 2.4.3 is a previously uncharacterized gene that has been designated nnrS. nnrS is only expressed when 2.4.3 is grown under denitrifying conditions. Expression of nnrS is dependent on the transcriptional regulator NnrR, which also regulates expression of genes required for the reduction of nitrite to nitrous oxide, including nirK and nor. Deletion analysis indicated the sequence 5'-TTGCG(N 4 )CACAA-3', which is similar to sequences found in nirK and nor, is required for nnrS expression. Mutation of this sequence to the consensus Fnr-binding sequence by changing two bases in each half site caused nnrS expression to become nitrate independent. Inactivation of nnrS did not affect nitric oxide metabolism, nor did it affect expression of any of the genes involved in nitric oxide metabolism. However, taxis towards nitrate and nitrite was affected by nnrS inactivation. Purification of a histidine-tagged NnrS demonstrated that NnrS is a haem-and copper-containing membrane protein.Genes encoding putative orthologues of NnrS are sometimes but not always found in bacteria encoding nitrite and/or nitric oxide reductase.

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Electron transport-dependent taxis in Rhodobacter sphaeroides

Cited by 44 publications

References 38 publications

Analysis of a chemotaxis operon from Rhodospirillum centenum

Analysis of a chemotaxis operon from Rhodospirillum centenum

The Aer protein and the serine chemoreceptor Tsr independently sense intracellular energy levels and transduce oxygen, redox, and energy signals for Escherichia coli behavior

Characterization of a member of the NnrR regulon in Rhodobacter sphaeroides 2.4.3 encoding a haem–copper protein The GenBank accession number for nnrS is U62403.

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