A minimal model for metabolism-dependent chemotaxis inRhodobacter sphaeroides

Abstract

Chemotaxis is vital cellular movement in response to environmental chemicals. Unlike the canonical chemotactic pathway in Escherichia coli , Rhodobacter sphaeroides has both transmembrane and cytoplasmic sensory clusters, with the latter possibly interacting with essential components in the electron transport system. However, the effect of the cytoplasmic sensor and the mechanism of signal integration from both sensory clusters remain unclear. Based on a minimal model of the chemotaxis pathway in this species, we show that signal integration at the motor level produces realistic chemotactic behaviour in line with experimental observations. Our model also suggests that the core pathway of R. sphaeroides , at least its ancestor, may represent a metabolism-dependent selective stopping strategy, which alone can steer cells to favourable environments. Our results not only clarify the potential roles of the two sensory clusters but also put in question the current definitions of attractants and repellents.

Enhancing the 1-Aminocyclopropane-1-Carboxylate Metabolic Rate of Pseudomonas sp. UW4 Intensifies Chemotactic Rhizocompetence

“…The increasing amount of available information enables us to understand how metabolism affects metabolism-dependent chemotaxis [35]. There are two hypotheses to explain the mechanism by which metabolism influences thechemotaxis: one is the proton motive force hypothesis [36], and the other is the ATP phosphorylation hypothesis [35]. The proton motive force hypothesis suggests that cell metabolism should generate a change in the intracellular proton motive force; subsequently, aerotaxis and phototaxis are mediated by the change.…”

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“…In the E. coli chemotaxis system, which also displays adaptive responses, ultrasensitivity is observed at the level of receptors and in the interaction of the signalling proteins with the motility apparatus [ 56 , 57 ]. It is thus also possible that ultrasensitivity is implemented within the chemotaxis signalling pathways [ 8 ] and might have underpinned an evolutionary step in generating adaptive response dynamics [ 18 , 58 ].…”

Theme Issue in memory of Tom Duke

“…Several contributions deal with the physics of bacteria and chemotaxis. Fan & Endres [2] present a model for chemotaxis, which depends on the cell metabolic state. In the case of metabolism-dependent chemotaxis, cells possess two types of receptors: (i) on the membrane to detect outside chemicals, and (ii) in the cytoplasm to detect metabolite levels in the cell.…”