A novel c-di-GMP effector linking intracellular virulence regulon to quorum sensing and hypoxia sensing

Abstract

Pathogenic bacteria have evolved sophisticated mechanisms to respond and adapt to diverse environmental conditions, especially at the early stage of host-pathogen interaction. Their ability to sense the change sat the infection court and to coordinate virulence gene expression among members, are critical for over whelming host defense responses and establishing infection. In a recently published paper, we have demonstrated that the Clp of X. campestris pv. campestris (Xcc),is a novel c-di-GMP binding protein. In this addendum, I intend to provide detailed discussion on the role and themechanism of Clp as a molecular link in connecting Xcc intracellular virulen ceregulon to quorum sensing and hypoxiasensing, which are two of the important environmental cues that influence the bacterial pathogenicity. In addition, I compare the c-di-GMP effector Clp with its close homologue Crp, which is a well-characterized cAMP receptor, in the context of ligand specificity, mode of action and their corresponding biological functions. The identification of Clp as a c-di-GMP receptor has provided further understanding howa bacterial pathogen could accommodate and integrate various signal inputs for its benefit. Significantly, this study has also presented solid evidence thatCrp-family proteins can be categorized into two functional groups, i.e., cAMP receptor and c-di-GMP effector, basedon the corresponding signature amino acid residues in the conserved cNMP binding domain. © 2010 Landes Bioscience.