Hypoxia‐induced localization of chemotaxis‐related signaling proteins in Vibrio cholerae

Abstract

SummaryVibrio cholerae has three sets of chemotaxis-related signaling proteins, of which only System II has been shown to be involved in chemotaxis. Here, we examined localization of green fluorescent protein (GFP)-fused components of System I. The histidine kinase (CheA1) and the adaptor (CheW0) of System I localized to polar and lateral membrane regions with standing incubation (microaerobic conditions), but their localization was lost after shaking (aerobic conditions). A transmembrane receptor of System I also showed polar and lateral localization with standing incubation. By contrast, GFP-fused components of System II localized constitutively to the flagellated pole. Nitrogen gas, sodium azide or carbonylcyanide m-chlorophenylhydrazone induced localization of CheA1-GFP even with shaking incubation, suggesting that the localization is controlled in response to changes in energy metabolism. Fluorescently labeled tetracysteine-tagged CheA1 also showed azideinduced localization, arguing against artifactual effects of GFP fusions. These results suggest that System I components are assembled into the supramolecular signaling complex in response to reduced cellular energy states, raising the possibility that the System I complex plays a role in sensing and signaling under microaerobic environments, such as in the host intestine.

The highly variable microbiota associated to intestinal mucosa correlates with growth and hypoxia resistance of sea bass, Dicentrarchus labrax, submitted to different nutritional histories

“…A longer exposure to hypoxia might favour the relative prevalence of Vibrio sp. OTU_7 in some resistant individuals, possibly by stimulating specific metabolic reactions as in Vibrio cholerae [36–38]. However, the fish were exposed to hypoxia for 6–8 h, and this range of variation seemed rather short to affect differentially intestinal microbiota.…”

RpoS and quorum sensing control expression and polar localization of Vibrio cholerae chemotaxis cluster III proteins in vitro and in vivo

“…In a recent study, cluster I chemotaxis proteins were observed to localize to polar and lateral membrane regions under microaerobic conditions (standing incubation). Localization was lost upon aeration (shaking incubation), suggesting that cluster I might be involved in sensing during oxygen deprivation (Hiremath et al, 2014). However, so far, no function has been observed for cluster I proteins, and it is unknown whether they contribute to chemotaxis (under specific, yet to be identified growth conditions), or instead mediate a process other than motility.…”

Microbial Surface Colonization and Biofilm Development in Marine Environments

“…Results to date show that chemotaxis can be important (399)(400)(401)(402)(403)(404)(405), advantageous (406), or dispensable (407) for initial surface colonization, indicating possible species-or strain-specific differences in the role of chemotaxis in microbial surface interactions or surface-or environment-specific differences in microbial chemotactic responses. Energy taxis can also be important to surface colonization by certain bacteria (408)(409)(410)(411). The microenvironment near a submerged surface is highly heterogeneous in that multiple gradients exist, including gradients of oxygen, pH, osmolarity, electron donors, electron acceptors, metabolizable substrates, redox potential, and chemical cues, including chemotactic attractants or repellents (34).…”