Analysis of the induction of general stress proteins of Bacillus subtilis

TLDR

In Bacillus subtilis, stress proteins are induced by various environmental conditions and are classified as general stress proteins (Gsps) and heat‑specific stress proteins (Hsps). The study aimed to determine the N‑terminal sequences of 13 Bacillus subtilis stress proteins. The authors performed N‑terminal sequencing to identify these proteins. Quantitative mRNA and protein synthesis analyses showed that DnaK and GroEL are heat‑specific chaperones, while GsiB, Ctc, and RsbW are general stress proteins induced by multiple stresses, and that SigB is essential for Gsp induction but not for Hsp induction during heat shock.

Abstract

In Bacillus subtilis stress proteins are induced in response to different environmental conditions such as heat shock, salt stress, glucose and oxygen limitation or oxidative stress. These stress proteins have been previously grouped into general stress proteins (Gsps) and heat-specific stress proteins (Hsps). In this investigation the N-terminal sequences of 13 stress proteins of B. subtilis were determined. The quantification of the mRNA and the analysis of the protein synthesis pattern support the initial hypothesis that the chaperones DnaK and GroEL are Hsps in B. subtilis. In contrast, the recently described proteins GsiB, Ctc and RsbW belong to a class of Gsps that are induced by various stresses including heat shock. The main part of the Gsps described in this study failed to be induced in the sigB deletion mutant ML6 in response to heat shock. However, all the five Hsps were induced in this mutant in response to heat shock. These data indicate that SigB plays a crucial role in the induction of general stress genes, but is dispensable for the induction of Hsps.