Biofilm formation by Bacillus subtilis requires an endoribonuclease‐containing multisubunit complex that controls mRNA levels for the matrix gene repressor SinR

Abstract

Biofilm formation by Bacillus subtilis is largely governed by a circuit in which the response regulator Spo0A turns on the gene for the anti-repressor SinI. SinI, in turn, binds to and inactivates SinR, a dedicated repressor of genes for matrix production. Mutants of the genes ylbF, ymcA, and yaaT are blocked in biofilm formation, but the mechanism by which they act has been mysterious. A recent report attributed their role in biofilm formation to stimulating Spo0A activity. However, we detect no measurable effect on the transcription of sinI. Instead, we find that the block in biofilm formation is caused by an increase in the levels of SinR and of its mRNA. Evidence is presented that YlbF, YmcA and YaaT interact with, and control the activity of, RNase Y, which is known to destabilize sinR mRNA. We show that the processing of another target of RNase Y, cggR-gapA mRNA, similarly depends on YlbF and YmcA. Our work suggests that sinR mRNA stability is an additional posttranscriptional control mechanism governing the switch to multicellularity and raises the possibility that YlbF, YmcA, and YaaT broadly regulate mRNA stability as part of an RNase Y-containing, multi-subunit complex.

Post‐transcriptionally generated cell heterogeneity regulates biofilm formation in Bacillus subtilis

“…; DeLoughery et al . ). Significant PyqhH and PyqhG promoter activities were observed in the lacZ analysis, compared to that of PsinI (Fig.…”

RNase Y-mediated regulation of the streptococcal pyrogenic exotoxin B

“…It has recently been shown that the processing by RNase Y of specific mRNA targets in B. subtilis depends on the so-called Y-complex, composed of RNase Y and interacting proteins [39,40]. Overall, the exact requirements for RNase Y activity in vivo still need to be determined, and current knowledge indicates that this enzyme may exhibit various characteristics in different bacteria.…”

The RicAFT (YmcA‐YlbF‐YaaT) complex carries two [4Fe‐4S]2+ clusters and may respond to redox changes

“…What might be the role of the RicAFT complex in B. subtilis, beyond stimulation of the phosphorelay? DeLoughery et al (2016) have proposed that the complex modulates mRNA processing via its association with the ribonuclease Rny. Indeed they have offered persuasive evidence that in ricF and ricA null mutants, the cggR-gapA mRNA is not processed normally.…”