Protein Domain : PilZ domain, Myxococcales-type IPR011752

Type	Domain
Description	The ubiquitous bacterial second messenger cyclic-di-GMP (c-di-GMP) is associated with the regulation of biofilm formation, the control of exopolysaccharide synthesis, flagellar- and pili-based motility, gene expression, interactions of bacteria with eukaryotic hosts and multicellular behaviour in diverse bacteria. This second messenger binds to PliZ domains from cytoplasmic receptors through its RXXXR and [D/N]hSXXG motifs []. However, some PilZ-related domains lack these motifs and do not bind c-di-GMP. The crystal structure, at 1.7 A, of a PilZ domain::c-di-GMP complex from Vibrio cholerae shows c-di-GMP contacting seven of nine strongly conserved residues. Binding of c-di-GMP causes a conformational switch whereby the C- and N-terminal domains are brought into close opposition forming a new allosteric interaction surface that spans these domains and the c-di-GMP at their interface []. Structural and sequence analysis of PilZ-related domains allow the description of three types of domains, the canonical PilZ domain (represented in this entry), whose structure includes a six-stranded β-barrel and a C-terminal alpha helix, an atypical PilZ domain containing two additional alpha helices and forms tetramers, and divergent PilZ-related domains, which include the PilZ protein and the YcgR N-terminal domains (PilZN and PilZNR). PilZN-type domains are evolutionarily related to PliZ domains and are found fused to the canonical PilZ domains in specific taxa, such as spirochetes, actinobacteria, aquificae, cellulose-degrading clostridia, and deltaproteobacteria [].Some examples of proteins containing this domain are BcsA subunits of bacterial cellulose synthases [ ] and flagellar brake protein YcgR (see ) [ ]. c-di-GMP binding to PilZ brings about conformational changes in the protein that stabilise the bound ligand and probability initiates the downstream signal transduction cascade. In the case of YcgR, c-di-GMP binding regulates flagellum-based motility in a c-di-GMP-dependent manner (see ) [ ]. The association of the PilZ domain with a variety of other domains, including likely components of bacterial multidrug secretion system, could provide clues to multiple functions of the c-di-GMP in bacterial pathogenesis and cell development.This entry represents a PilZ domain found mainly in Myxococcales.
Short Name	PilV_Myxo-type