The Highly Conserved MraZ Protein Is a Transcriptional Regulator in Escherichia coli

Abstract

The mraZ and mraW genes are highly conserved in bacteria, both in sequence and in their position at the head of the division and cell wall (dcw) gene cluster. Located directly upstream of the mraZ gene, the P mra promoter drives the transcription of mraZ and mraW, as well as many essential cell division and cell wall genes, but no regulator of P mra has been found to date. Although MraZ has structural similarity to the AbrB transition state regulator and the MazE antitoxin and MraW is known to methylate the 16S rRNA, mraZ and mraW null mutants have no detectable phenotypes. Here we show that overproduction of Escherichia coli MraZ inhibited cell division and was lethal in rich medium at high induction levels and in minimal medium at low induction levels. Co-overproduction of MraW suppressed MraZ toxicity, and loss of MraW enhanced MraZ toxicity, suggesting that MraZ and MraW have antagonistic functions. MraZ-green fluorescent protein localized to the nucleoid, suggesting that it binds DNA. Consistent with this idea, purified MraZ directly bound a region of DNA containing three direct repeats between P mra and the mraZ gene. Excess MraZ reduced the expression of an mraZ-lacZ reporter, suggesting that MraZ acts as a repressor of P mra , whereas a DNA-binding mutant form of MraZ failed to repress expression. Transcriptome sequencing (RNA-seq) analysis suggested that MraZ also regulates the expression of genes outside the dcw cluster. In support of this, purified MraZ could directly bind to a putative operator site upstream of mioC, one of the repressed genes identified by RNA-seq.

Hydrogen Sulfide and Reactive Sulfur Species Impact Proteome S-Sulfhydration and Global Virulence Regulation in Staphylococcus aureus

“…Of special interest are several transcriptional regulators, including the heat shock regulator CtsR that controls the expression of the clp protease genes linked to virulence, 38 the alternative sigma factor SigB, a global stress response regulator that regulates the transcription of the global regulator SarA, 39 RsbU, which regulates the expression of SigB, 40 and an uncharacterized dithiol-containing TetR-family repressor, NWMN_2477, and all are detected as S -sulfhydrated in cells. Other regulators, including WhiA, which controls sporulation, 41 MraZ, which regulates cell division, 42 and HssR, a heme response regulator, 43 are also S -sulfhydrated, suggesting that these regulators may be subject to redox-regulation as potential targets for H 2 S signaling.…”

The Conserved Dcw Gene Cluster of R. sphaeroides Is Preceded by an Uncommonly Extended 5’ Leader Featuring the sRNA UpsM

“…In E . coli the first promoter ( mraZ 1 p ) of the gene cluster (16 genes in total) gives rise to polycistronic transcripts containing a short 38nt long 5’ UTR followed by the first gene mraZ [4, 7]. However, in this study we have been able to describe a much longer 5’ UTR of 268 nt in length featuring trans- regulatory and potential cis -regulatory elements (summarized in S7 Fig).…”

“…This is surprising since mraZ is the first gene of the dcw gene cluster. Therefore it should be expressed in exponentially growing cells in the course of cell wall synthesis and cell division as described for other bacteria [4, 7–11]. This observation led to the following assumptions: MraZ transcription depends on the UpsM promoter and there is no additional promoter/TSS exclusively present for mraZ .…”

Reconstruction of Transcription Control Networks in Mollicutes by High-Throughput Identification of Promoters

“…MraZ is conserved in spiroplasmas and mycoplasmas, whereas WhiA is conserved in all Mollicutes. The role of MraZ is more or less known (Fisunov et al, 2016) and appears to be widespread in Bacteria (Eraso et al, 2014); the function of WhiA as a cell division regulator was demonstrated only for Streptomyces coelicolor (Jakimowicz et al, 2006). In this bacterium, the WhiA-family TF was shown to regulate parAB and ftsZ genes.…”