The Behavioural Response of Anaerobic Rhodobacter Sphaeroides to Temporal Stimuli

Packer, Helen L.; Gauden, David E.; Armitage, Judith P.

doi:10.1099/13500872-142-3-593

Cited by 26 publications

(35 citation statements)

References 23 publications

(31 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5). This response to a decrease, but not an increase, in a light stimulus is very similar to the chemotactic response of R. sphaeroides (20). This "behavioral pessimism" is in contrast to enteric species, which show a greater response to the addition of an attractant than to its removal (25).…”

Section: Resultsmentioning

confidence: 50%

Photoresponses in Rhodobacter sphaeroides: role of photosynthetic electron transport

1997

View full text Add to dashboard Cite

Rhodobacter sphaeroides responds to a decrease in light intensity by a transient stop followed by adaptation. There is no measurable response to increases in light intensity. We confirmed that photosynthetic electron transport is essential for a photoresponse, as (i) inhibitors of photosynthetic electron transport inhibit photoresponses, (ii) electron transport to oxidases in the presence of oxygen reduces the photoresponse, and (iii) the magnitude of the response is dependent on the photopigment content of the cells. The photoresponses of cells grown in high light, which have lower concentrations of light-harvesting photopigment and reaction centers, saturated at much higher light intensities than the photoresponses of cells grown in low light, which have high concentrations of light-harvesting pigments and reaction centers. We examined whether the primary sensory signal from the photosynthetic electron transport chain was a change in the electrochemical proton gradient or a change in the rate of electron transport itself (probably reflecting redox sensing). R. sphaeroides showed no response to the addition of the proton ionophore carbonyl cyanide 4-trifluoromethoxyphenylhydrazone, which decreased the electrochemical proton gradient, although a behavioral response was seen to a reduction in light intensity that caused an equivalent reduction in proton gradient. These results strongly suggest that (i) the photosynthetic apparatus is the primary photoreceptor, (ii) the primary signal is generated by a change in the rate of electron transport, (iii) the change in the electrochemical proton gradient is not the primary photosensory signal, and (iv) stimuli affecting electron transport rates integrate via the electron transport chain.

show abstract

Section: Resultsmentioning

confidence: 50%

Photoresponses in Rhodobacter sphaeroides: role of photosynthetic electron transport

1997

View full text Add to dashboard Cite

show abstract

“…Under these conditions, ⌬⌿ increased but the rate of aerobic respiration decreased. All previous data suggest that R. sphaeroides responds chemotactically primarily to a stimulus decrease under these conditions (28). Therefore, the response to FCCP removal suggests that electron transport-dependent taxis normally senses not ⌬⌿ but the rate of electron transport, probably as a change in the redox state of one of the intermediate carriers.…”

Section: Discussionmentioning

confidence: 91%

“…The Seescan system produces rotation rate measurements for individual cells over sequential 0.06 s intervals. The behavior of tethered R. sphaeroides cells is such that they are either rotating or have stopped (28), unlike that of tethered E. coli cells (4), which alternate between clockwise rotation and counterclockwise rotation. Because of the above property and by using the rotation data, we can define a tethered cell of R. sphaeroides as either rotating or stopped at a specific time.…”

mentioning

confidence: 99%

Electron transport-dependent taxis in Rhodobacter sphaeroides

Gauden

Armitage

1995

J Bacteriol

View full text Add to dashboard Cite

Rhodobacter sphaeroides showed chemotaxis to the terminal electron acceptors oxygen and dimethyl sulfoxide, and the responses to these effectors were shown to be influenced by the relative activities of the different electron transport pathways. R. sphaeroides cells tethered by their flagella showed a step-down response to a decrease in the oxygen or dimethyl sulfoxide concentration when using them as terminal acceptors. Bacteria using photosynthetic electron transport, however, showed a step-down response to oxygen addition. Addition of the proton ionophore carbonyl cyanide 4-trifluoromethoxyphenylhydrazone did not cause a transient behavioral response, although it decreased the electrochemical proton gradient (⌬p) and increased the rate of electron transport. However, removal of the ionophore, which caused an increase in ⌬p and a decrease in the electron transport rate, resulted in a step-down response. Together, these data suggest that behavioral responses of R. sphaeroides to electron transport effectors are caused by changes in the rate of electron transport rather than changes in ⌬p.The purple nonsulfur phototroph Rhodobacter sphaeroides is a motile, chemotactic bacterium capable of growth and division under a wide range of conditions, including aerobic heterotrophic, anaerobic phototrophic, anaerobic photoheterotrophic, and dark anaerobic conditions, using an alternative electron acceptor like dimethyl sulfoxide (DMSO) or trimethylamine-N-oxide. To grow and divide under these different conditions, R. sphaeroides can induce a range of alternative oxidases and terminal reductases, including one for DMSO and trimethylamine-N-oxide. Not all of the different carriers and terminal reductases are induced to high levels under all conditions, and there appears to be some redundancy. For example, during anaerobic growth in the dark using DMSO or trimethylamine-N-oxide as an electron acceptor, R. sphaeroides synthesizes a full complement of photosynthetic pigments, as well as the ''alternative'' cytochrome b 260 oxidase (38), and during anaerobic photoheterotrophic growth, both the b 260 and b 410 (KCN-sensitive) oxidases are induced (22,39). This redundancy allows R. sphaeroides populations to respond rapidly, in terms of electron transport, to changes in their environment.Previous work on the phenomenon of aerotaxis in Escherichia coli and Salmonella typhimurium has indicated that it is independent of the methyl-accepting chemotaxis proteins used as part of the primary sensing system in these organisms (26, 34), although methyl-accepting chemotaxis proteins have been implicated in aerotaxis in Bacillus subtilis (37). R. sphaeroides appears to have a chemotaxis system comprising both methylaccepting chemotaxis protein-dependent and -independent pathways (36). This, in conjunction with its flexible electron transport system, makes R. sphaeroides an interesting organism for the study of taxis to effectors linked to electron transport. Aerotaxis and phototaxis in the purple photosynthetic bacteria were first identifie...

show abstract

“…Alternatively, PE may increase the speed of twitching motility, and therefore directed movement may be the product of chemokinesis. Unlike chemotaxis, chemokinesis in Rhodobacter sphaeroides (23) and M. xanthus (28) does not show adaptation, and thus the effect on motility is independent of a gradient. To distinguish between chemotactic and chemokinetic responses in P. aeruginosa, cells were spotted onto a uniform concentration of PE.…”

mentioning

confidence: 99%

Pseudomonas aeruginosa Exhibits Directed Twitching Motility Up Phosphatidylethanolamine Gradients

2001

View full text Add to dashboard Cite

Pseudomonas aeruginosa translocates over solid surfaces by a type IV pilus-dependent form of multicellular motility known as twitching. We wondered whether cells utilize endogenous factors to organize twitching, and we purified from wild-type cells a lipid that caused directed movement. Wild-type P. aeruginosa, but not a pilJ pilus-deficient mutant, showed biased movement up gradients of phosphatidylethanolamine (PE) established in agar. Activity was related to the fatty acid composition of the lipid, as two synthetic PE species, dilauroyl and dioleoyl PE, were capable of directing P. aeruginosa motility while many other species were inactive. P. aeruginosa PE did not contain either laurate or oleate, implying that the native attractant species contains different fatty acids. Uniform concentrations of PE increased cell velocity, suggesting that chemokinesis may be at least partly responsible for directed movement. We speculate that PE-directed twitching motility may be involved in biofilm formation and pathogenesis.

show abstract

The Behavioural Response of Anaerobic Rhodobacter Sphaeroides to Temporal Stimuli

Cited by 26 publications

References 23 publications

Photoresponses in Rhodobacter sphaeroides: role of photosynthetic electron transport

Photoresponses in Rhodobacter sphaeroides: role of photosynthetic electron transport

Electron transport-dependent taxis in Rhodobacter sphaeroides

Pseudomonas aeruginosa Exhibits Directed Twitching Motility Up Phosphatidylethanolamine Gradients

Contact Info

Product

Resources

About