The HD-GYP Domain and Cyclic Di-GMP Signaling

Abstract

A role for the HD-GYP domain in c-di-GMP hydrolysis was then proposed based on examination of the distribution and numbers of GGDEF, EAL, and HD-GYP domains encoded by different bacterial genomes, coupled with the known activities of other members of the HD superfamily of enzymes as metal-dependent hydrolases. This chapter reviews the current understanding of the HD-GYP domain in c-di-GMP signaling. In particular, it discusses (i) the identification of the HD-GYP domain and bioinformatic prediction as a novel c-di-GMP PDE, (ii) the experimental evidence implicating the HD-GYP domain in c-di-GMP degradation, (iii) the biological role of the HD-GYP domain protein RpfG in signal transduction in Xcc, (iv) regulatory interplay between RpfG and other c-di-GMP signaling proteins in Xcc, and (v) emerging information on the role of HD-GYP domain proteins in other bacteria. A role for HD-GYP in c-di-GMP hydrolysis was proposed based on an examination of the distribution and numbers of GGDEF, EAL, and HD-GYP domains encoded by different bacterial genomes, where several genomes encode proteins with the GGDEF and HD-GYP domains but no EAL domain. These findings illustrate two aspects of HD-GYP domain proteins that are consonant with our understanding of the diverse roles of GGDEF and EAL domain proteins. The first is that different HD-GYP domain proteins appear to have distinct regulatory roles.