An Oxygen-Sensing Diguanylate Cyclase and Phosphodiesterase Couple for c-di-GMP Control

Abstract

A commonly observed coupling of sensory domains to GGDEF-class diguanylate cyclases and EAL-class phosphodiesterases has long suggested that c-di-GMP synthesizing and degrading enzymes sense environmental signals. Nevertheless, relatively few signal ligands have been identified for these sensors, and even fewer instances of in vitro switching by ligand have been demonstrated. Here we describe an Escherichia coli two-gene operon, dosCP, for control of c-di-GMP by oxygen. In this operon, the gene encoding the oxygen-sensing c-di-GMP phosphodiesterase Ec Dos (here renamed Ec DosP) follows and is translationally coupled to a gene encoding a diguanylate cyclase, here designated DosC. We present the first characterizations of DosC and a detailed study of the ligand-dose response of DosP. Our results show that DosC is a globin-coupled sensor with an apolar but accessible heme pocket that binds oxygen with a K(d) of 20 microM. The response of DosP activation to increasing oxygen concentration is a complex function of its ligand saturation such that over 80% of the activation occurs in solutions that exceed 30% of air saturation (oxygen >75 microM). Finally, we find that DosP and DosC associate into a functional complex. We conclude that the dosCP operon encodes two oxygen sensors that cooperate in the controlled production and removal of c-di-GMP.

Self-produced exopolysaccharide is a signal that stimulates biofilm formation inPseudomonas aeruginosa

“…In P. aeruginosa, the diguanylate cyclases SiaD and WspR are activated upon exposure to SDS or contact with solid surfaces, respectively (15)(16)(17). In Escherichia coli, the activity of the DosCP cyclase/phosphodiesterase pair is modulated by oxygen availability (18), whereas diffusible signal factor was shown to activate c-di-GMP phosphodiesterase activity through the two-component regulatory system RpfG/C in Xanthomonas campestris (19). In addition, blue light was demonstrated to activate the c-di-GMP phosphodiesterase activity of BlrP1 in Klebsiella pneumoniae (20).…”

Identification and Functional and Spectral Characterization of a Globin-coupled Histidine Kinase from Anaeromyxobacter sp. Fw109-5

“…The structures of the globin fold of GCS enzymes are similar to those of myoglobin and hemoglobin but lack the entire D-and half of the E-helices of these proteins. Six heme-based oxygen sensor proteins, YddV (27,28), HemAT-Bs (29 -32), AvGReg (33), BpeGReg (34), GsGCS (35), and HemDGC (36), with the globin fold have been identified to date. Although both the sensor histidine kinase in the two-component system and GCS protein are important for bacteria to survive and/or to accommodate various stresses, no globin-coupled heme-regulated histidine kinases (GcHK) have been documented to date.…”

Genomic sequencing-based mutational enrichment analysis identifies motility genes in a genetically intractable gut microbe

“…In addition to GGDEF and EAL domains, Ea2862 also has a PAS domain that is predicted to sense small molecules such as metabolites and gases (33). Indeed, the automated PROKKA annotation program ascribed Ea2862 as a homolog of the oxygen-sensing protein DosP (34). In B. subtilis, loss of the EAL protein PdeH causes elevated levels of c-di-GMP that inhibit motility through the PilZ domain protein YpfA and the flagellar motor protein MotA (31,35,36).…”