Evidence for Cyclic Di-GMP-Mediated Signaling in Bacillus subtilis

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>Cyclic di-GMP (c-di-GMP) is a second messenger that regulates diverse cellular processes in bacteria, including motility, biofilm formation, cell-cell signaling, and host colonization. Studies of c-di-GMP signaling have chiefly focused on Gram-negative bacteria. Here, we investigated c-di-GMP signaling in the Gram-positive bacterium<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Bacillus subtilis</jats:named-content>by constructing deletion mutations in genes predicted to be involved in the synthesis, breakdown, or response to the second messenger. We found that a putative c-di-GMP-degrading phosphodiesterase, YuxH, and a putative c-di-GMP receptor, YpfA, had strong influences on motility and that these effects depended on sequences similar to canonical EAL and RxxxR—D/NxSxxG motifs, respectively. Evidence indicates that YpfA inhibits motility by interacting with the flagellar motor protein MotA and that<jats:italic>yuxH</jats:italic>is under the negative control of the master regulator Spo0A∼P. Based on these findings, we propose that YpfA inhibits motility in response to rising levels of c-di-GMP during entry into stationary phase due to the downregulation of<jats:italic>yuxH</jats:italic>by Spo0A∼P. We also present evidence that YpfA has a mild influence on biofilm formation.<jats:italic>In toto</jats:italic>, our results demonstrate the existence of a functional c-di-GMP signaling system in<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">B. subtilis</jats:named-content>that directly inhibits motility and directly or indirectly influences biofilm formation.</jats:p>

Two DHH Subfamily 1 Proteins in Streptococcus pneumoniae Possess Cyclic Di-AMP Phosphodiesterase Activity and Affect Bacterial Growth and Virulence

“…The majority of diguanylate cyclases have been identified in Gram-negative bacteria, whereas diadenylate cyclases have been reported mostly in Gram-positive bacteria. The presence of c-di-GMP signaling in Gram-positive bacteria has been directly demonstrated only in B. subtilis (55,56) and the spore-forming, obligate anaerobe Clostridium difficile (57). We were unable to find any GGDEF motif in S. pneumoniae proteins.…”

Evolution of exploitative interactions during diversification in Bacillus subtilis biofilms

“…As c-di-GMP plays an important role in motility arrest (Chen et al 2012a), mutation in GMP synthetize GuaA probably reduces the level of c-di-GMP possibly enhancing motility.…”

Cyclic Di-AMP Homeostasis in Bacillus subtilis

“…The genome of B. subtilis encodes several potential diguanylate cyclases and potential c-di-GMP-specific phosphodiesterases (13,14). Very recently, c-di-GMP was found to control motility by binding the YpfA protein, which in turn interacts with and inhibits the motor protein MotA in B. subtilis (14). In addition to these well established signaling nucleotides, c-di-AMP synthesis by the DisA protein was recently discovered for the first time (7).…”

“…Moreover, ppGpp mediates the stringent response by inhibiting GTP synthesis and thus by differential control of transcription of mRNAs that use an A or a G as the first nucleotide (10 -12). The genome of B. subtilis encodes several potential diguanylate cyclases and potential c-di-GMP-specific phosphodiesterases (13,14). Very recently, c-di-GMP was found to control motility by binding the YpfA protein, which in turn interacts with and inhibits the motor protein MotA in B. subtilis (14).…”