Genetic evidence for involvement of the alternative sigma factor SigI in controlling expression of the cell wall hydrolase gene lytE and contribution of LytE to heat survival of Bacillus subtilis

Abstract

The Bacillus subtilis cell wall hydrolase LytE is involved in cell wall turnover and cell separation during vegetative growth. lytE transcription is known to be driven by a YycF-activated SigA-dependent promoter. The cell wall regulator SigI is an alternative sigma factor that has been shown to be heat stress-inducible and to be essential for survival of B. subtilis at high temperature. However, none of the previously identified target genes of SigI contribute to heat resistance. We now demonstrate that lytE expression is heat-inducible and that heat induction of lytE expression is strongly dependent on SigI. We have also found that the lytE mutant shows the same growth defect at high temperature as the sigI mutant. Introducing an extra copy of lytE into the sigI mutant could rescue its growth defect. Our data strongly suggest that SigI-dependent lytE expression under heat stress is important for heat survival of B. subtilis.

Teichoic Acid Polymers Affect Expression and Localization of dl -Endopeptidase LytE Required for Lateral Cell Wall Hydrolysis in Bacillus subtilis

“…Both lytE and cwlO are in the WalRK regulon (14). In addition, lytE transcription is regulated by I , which is required for heat shock adaptation (15,16) and is enhanced at high temperatures (17). Moreover, the DL-endopeptidase activity of LytE is essential for survival at high temperatures (17).…”

“…In addition, lytE transcription is regulated by I , which is required for heat shock adaptation (15,16) and is enhanced at high temperatures (17). Moreover, the DL-endopeptidase activity of LytE is essential for survival at high temperatures (17). It is thought that LytE digests not only septum PG but also sidewall PG to allow newly synthesized PG precursors to be incorporated (12).…”

Expressions of alkaline phosphatase genes during phosphate starvation are under positive influences of multiple cell wall hydrolase genes in <i>Bacillus subtilis</i>

“…During phosphate starvation, the two-component system PhoPR of Bacillus subtilis activates transcription of APase genes (phoA, phoB, and phoD) to generate free phosphate groups for uptake and utilization (Allenby et al, 2005;Antelmann et al, 2000). Among the vegetatively expressed cell wall hydrolase genes lytC, lytD, lytE, lytF, cwlO, and cwlS of B. subtilis, only lytE and cwlO are not regulated by SigD (Chen et al, 2009;Huang et al, 2013;Noone et al, 2014;Tseng et al, 2011). It has been reported that LytE and CwlO are required for cell elongation and that cells lacking both enzymes exhibit a synthetic lethal phenotype (Bisicchia et al, 2007;Hashimoto et al, 2012).…”

“…Given the co-induction of lytE and phoA by heat stress (Helmann et al, 2001;Huang et al, 2013;Tseng et al, 2011) and the co-inhibition of the levels of LytE and PhoA by Spo0A in B. subtilis (Hulett et al, 1994;Jensen et al, 1993;Kodama et al, 2007), we wondered whether there would be other correlation(s) between expression of lytE and phoA. Firstly, effect of mutation of lytE on transcription of phoA was investigated by using PCR and the primer pair A64 plus A65 (Table S1) to construct the pDLbased integrative plasmid pGS2095 (Table 1), which carries a transcriptional fusion of the regulatory region of phoA with bgaB.…”

“…2C), suggesting that the influence of lytE on expression of APase genes is, at least in part, not mediated through PhoP and may involve other regulatory mechanism. ; integration vector used for gene disruption (Fedhila et al, 2002) pENB11 pRN5101 carrying an internal region close to the N terminus of lytE (+17 to +372 relative to the translational start site of lytE) (Tseng et al, 2011) pENB12 pRN5101 carrying an internal region close to the N terminus of lytD (+67 to +427 relative to the translational start site of lytD) (Tseng et al, 2011) pENB14 pDL carrying the regulatory and coding regions of lytE (−327 to +1079) (Tseng et al, 2011 pDL carrying the regulatory region of phoA (−276 to +89) This study pGS2117 pDL carrying the regulatory region of phoP (−350 to +112 relative to the translational start site of phoP) This study pGS2136 pRN5101 carrying an internal region close to the N terminus of lytF (+55 to +348 relative to the translational start site of lytF) This study pGS2137 pDL carrying the regulatory region of phoB (−320 to +37 relative to the translational start site of phoB) This study pGS2738 pDL carrying the regulatory region of phoD (−470 to −16 relative to the translational start site of phoD) This study Table 1. Bacterial strains and plasmids used in this study.…”