DgrA is a member of a new family of cyclic diguanosine monophosphate receptors and controls flagellar motor function in Caulobacter crescentus

Abstract

Bacteria are able to switch between two mutually exclusive lifestyles, motile single cells and sedentary multicellular communities that colonize surfaces. These behavioral changes contribute to an increased fitness in structured environments and are controlled by the ubiquitous bacterial second messenger cyclic diguanosine monophosphate (c-di-GMP). In response to changing environments, fluctuating levels of c-di-GMP inversely regulate cell motility and cell surface adhesins. Although the synthesis and breakdown of c-di-GMP has been studied in detail, little is known about the downstream effector mechanisms. Using affinity chromatography, we have isolated several c-di-GMP-binding proteins from Caulobacter crescentus . One of these proteins, DgrA, is a PilZ homolog involved in mediating c-di-GMP-dependent control of C. crescentus cell motility. Biochemical and structural analysis of DgrA and homologs from C. crescentus , Salmonella typhimurium , and Pseudomonas aeruginosa demonstrated that this protein family represents a class of specific diguanylate receptors and suggested a general mechanism for c-di-GMP binding and signal transduction. Increased concentrations of c-di-GMP or DgrA blocked motility in C. crescentus by interfering with motor function rather than flagellar assembly. We present preliminary evidence implicating the flagellar motor protein FliL in DgrA-dependent cell motility control.

Radiation-sensitive Gene A (RadA) Targets DisA, DNA Integrity Scanning Protein A, to Negatively Affect Cyclic Di-AMP Synthesis Activity in Mycobacterium smegmatis

“…Thus, we found a novel mechanism of control of bacterial c-di-AMP synthesis via RadA-DisA interaction in M. smegmatis. In recent years, accumulating evidence has shown that cyclic dinucleotides widely function as second messengers that control multiple microbial phenotypes and physiological characteristics (4,5,(25)(26)(27)(28). Compared with the clearly characterized functions for c-di-GMP in many bacteria (4,5,28), much less is known about the control of c-di-AMP synthesis and its effects on bacterial growth.…”

Functioning in situ: gene expression in Methylotenera mobilis in its native environment as assessed through transcriptomics

“…Although the product of fliL is essential for flagellar rotation, it is not considered a part of the hierarchy of the flagellum structure (Jenal et al, 1994). Instead, it has been suggested to have a role in controlling the switch between swimming and surface-associated lifestyles (Christen et al, 2007). Upregulation of fliL in the presence of methylamine thus may reflect a mechanism of activation of the flagellum machinery in response to the availability of a carbon source.…”

“…A motile cell can quickly reach a favorable niche in response to external stimuli and thus can successfully compete for a nutrient. However, synthesis and maintenance of the motility systems are energetically costly for the cell, and the motility functions are known to be tightly regulated by the availability of essential nutrients (Zhao et al, 2007;Christen et al, 2007). M. mobilis cells have been shown to be motile when grown in standard laboratory conditions (Kalyuzhnaya et al, 2006).…”

LapD is a bis-(3′,5′)-cyclic dimeric GMP-binding protein that regulates surface attachment by Pseudomonas fluorescens Pf0–1

“…The first class, PilZ-domain proteins, has been linked to regulation of flagellar motility in Enterobacteria, Vibrio, and Caulobacter (10)(11)(12) and to the synthesis of alginate and type IV pili in Pseudomonas (13,14). The second class is less defined but shares an amino acid motif, RxxD, first identified as the allosteric site of product feedback inhibition in the diguanylate cyclase (DGC) PleD (15).…”