Abstract
Environmental changes trigger the continuous adaptation of bacteria to ensure their survival. This is possible through a variety of signal transduction pathways involving chemoreceptors known as methyl-accepting chemotaxis proteins (MCP) that allow the microorganisms to redirect their mobility towards favorable environments. MCP are two-component regulatory (or signal transduction) systems (TCS) formed by a sensor and a response regulator domain. These domains synchronize transient protein phosphorylation and dephosphorylation events to convert the stimuli into an appropriate cellular response. In this review, the variability of TCS domains and the most common signaling mechanisms are highlighted. This is followed by the description of the overall cellular topology, classification and mechanisms of MCP. Finally, the structural and functional properties of a new family of MCP found in Geobacter sulfurreducens are revisited. This bacterium has a diverse repertoire of chemosensory systems, which represents a striking example of a survival mechanism in challenging environments. Two G. sulfurreducens MCP—GSU0582 and GSU0935—are members of a new family of chemotaxis sensor proteins containing a periplasmic PAS-like sensor domain with a c-type heme. Interestingly, the cellular location of this domain opens new routes to the understanding of the redox potential sensing signaling transduction pathways.
Highlights
This review focuses on a particular group of chemoreceptors known as two-component systems (TCS)
TCS are abundant multistep signaling pathways that respond to a wide range of stimulus
For a large majority of TCS, how physiological signals modulate their action is not precisely understood; such studies have provided crucial information regarding the modus operandi of TCS
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. TCS are found in organisms of all domains (Bacteria, Archaea, and Eukarya); their abundance in each domain differs substantially [1]. They are abundant in most Bacteria and constitute about ∼1% of the encoded proteins. The Escherichia coli (E. coli) genome encodes for 62 TCS proteins that are involved in the regulation of several processes, namely chemotaxis, osmoregulation, cellular metabolism and biological transport [2]. In Archaea and Eukarya, the TCS pathways constitute only a small number of the available signaling systems, though they mediate the environmental stress responses in fungi [5,6] and the hyphal development in pathogenic yeasts [7,8]. Animals and humans seem to constitute an exception, as TCS have not yet been identified [11,12,13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
