Dataset Information

In vivo mutational analysis of YtvA from Bacillus subtilis: mechanism of light activation of the general stress response.

ABSTRACT: The general stress response of Bacillus subtilis can be activated by stimuli such as the addition of salt or ethanol and with blue light. In the latter response, YtvA activates sigma(B) through a cascade of Rsb proteins, organized in stressosomes. YtvA is composed of an N-terminal LOV (light, oxygen, and voltage) domain and a C-terminal STAS (sulfate transporter and anti-sigma factor) domain and shows light-modulated GTP binding in vitro. Here, we examine the mechanism of YtvA-mediated activation of sigma(B) in vivo with site-directed mutagenesis. Constitutive off and constitutive on mutations have been identified. Disruption of GTP binding in the STAS domain eliminates light activation of sigma(B). In contrast, modification of sites relevant for phosphorylation of STAS domains does not affect the stress response significantly. The data obtained are integrated into a model for the structure of full-length YtvA, which presumably functions as a dimer.

SUBMITTER: Avila-Perez M

PROVIDER: S-EPMC2757199 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

In vivo mutational analysis of YtvA from Bacillus subtilis: mechanism of light activation of the general stress response.

Avila-Pérez Marcela M Vreede Jocelyne J Tang Yifen Y Bende Onno O Losi Aba A Gärtner Wolfgang W Hellingwerf Klaas K

The Journal of biological chemistry 20090706 37

The general stress response of Bacillus subtilis can be activated by stimuli such as the addition of salt or ethanol and with blue light. In the latter response, YtvA activates sigma(B) through a cascade of Rsb proteins, organized in stressosomes. YtvA is composed of an N-terminal LOV (light, oxygen, and voltage) domain and a C-terminal STAS (sulfate transporter and anti-sigma factor) domain and shows light-modulated GTP binding in vitro. Here, we examine the mechanism of YtvA-mediated activatio ...[more]

PMID: 19581299

Similar Datasets

Project description:Gene arrays containing all currently known open reading frames of Bacillus subtilis were used to examine the general stress response of Bacillus. By proteomics, transcriptional analysis, transposon mutagenesis, and consensus promoter-based screening, 75 genes had previously been described as sigma(B)-dependent general stress genes. The present gene array-based analysis confirmed 62 of these already known general stress genes and detected 63 additional genes subject to control by the stress sigma factor sigma(B). At least 24 of these 125 sigma(B)-dependent genes seemed to be subject to a second, sigma(B)-independent stress induction mechanism. Therefore, this transcriptional profiling revealed almost four times as many regulon members as the proteomic approach, but failure of confirmation of all known members of the sigma(B) regulon indicates that even this approach has not yet elucidated the entire regulon. Most of the sigma(B)-dependent general stress proteins are probably located in the cytoplasm, but 25 contain at least one membrane-spanning domain, and at least 6 proteins appear to be secreted. The functions of most of the newly described genes are still unknown. However, their classification as sigma(B)-dependent stress genes argues that their products most likely perform functions in stress management and help to provide the nongrowing cell with multiple stress resistance. A comprehensive screening program analyzing the multiple stress resistance of mutants with mutations in single stress genes is in progress. The first results of this program, showing the diminished salt resistance of yjbC and yjbD mutants compared to that of the wild type, are presented. Only a few new sigma(B)-dependent proteins with already known functions were found, among them SodA, encoding a superoxide dismutase. In addition to analysis of the sigma(B)-dependent general stress regulon, a comprehensive list of genes induced by heat, salt, or ethanol stress in a sigma(B)-independent manner is presented. Perhaps the most interesting of the sigma(B)-independent stress phenomena was the induction of the extracytoplasmic function sigma factor sigma(W) and its entire regulon by salt shock.

Project description:Seemingly simple bacteria mount intricate adaptive responses when exposed to physical stress or nutrient limitation, and the activation of these responses is governed by complex signal transduction networks. Upon entry into the stationary growth phase, the soil bacterium Bacillus subtilis may develop natural competence, form biofilms or stress-resistant cells, or ultimately trigger a cellular differentiation program leading to spore formation. Master regulators, such as Spo0A, ComK, SinR, and SigB, constantly monitor the bacterium's environment and then determine appropriate adaptive responses. Here, we show that exposure of B. subtilis to visible light and other stresses triggers a general stress response-dependent block in competence development. SigB serves as an "emergency system" to silence inappropriate expression of an alternative developmental program in the face of unfavorable conditions. In particular, we document a stress-dependent molecular mechanism that prevents accumulation of the central competence regulator ComK via expression of a SigB-driven antisense RNA (as-comK, S365) which is part of a noncontiguous operon.ImportanceBacillus subtilis exhibits a large number of different specific and general adaptation reactions, which need to be well balanced to sustain survival under largely unfavorable conditions. Under specific conditions, natural competence develops, which enables B. subtilis to actively take up exogenous DNA to integrate it into its own genome. In contrast to this specific adaptation, the general stress response is induced by a variety of exogenous stress and starvation stimuli, providing comprehensive protection and enabling survival of vegetative B. subtilis cells. In the present work, we reveal the molecular basis for the interconnection of these two important responses in the regulatory network. We describe that the master regulator of the general stress response SigB is activated by physiological stress stimuli, including daylight and ethanol stress, leading to the inactivation of the competence master regulator ComK by transcriptional anti-sense regulation, showing a strict hierarchy of adaptational responses under severe stress.

Project description:The sigma(B)-dependent general stress regulon of Bacillus subtilis comprises more than 150 members. Induction of this regulon by imposition of environmental or metabolic stress confers multiple, nonspecific, and preemptive stress resistance to nongrowing, nonsporulated cells of B. subtilis. In this study we performed a regulon-wide phenotypic screening analysis to determine the stress sensitivity profiles of 94 mutants defective in candidate members of the general stress regulon that were previously identified in our transcriptional profiling study of the general stress response of B. subtilis. The phenotypic screening analysis included analysis of adaptation to a growth-inhibiting concentration of ethanol (10%, vol/vol) or NaCl (10%, wt/vol), severe heat shock (54 degrees C), and low temperature (survival at 4 degrees C and growth at 12.5 degrees C). Surprisingly, 85% of the mutants tested displayed increased sensitivity at an alpha confidence level of < or =0.01 to at least one of the four stresses tested, and 62% still exhibited increased sensitivity at an alpha of < or =0.001. In essence, we were able to assign 63 genes (28 genes with an alpha of < or =0.001) to survival after ethanol shock, 37 genes (28 genes with an alpha of < or =0.001) to protection from NaCl shock, 34 genes (24 genes with an alpha of < or =0.001) to survival at 4 degrees C, and 10 genes (3 genes with an alpha of < or =0.001) to management of severe heat shock. Interestingly, there was a substantial overlap between the genes necessary for survival during ethanol shock and the genes necessary for survival at 4 degrees C, and there was also an overlap between genes required for survival during ethanol shock and genes required for survival during NaCl shock. Our data provide evidence for the importance of the sigma(B) regulon at low temperatures, not only for growth but also for survival. Moreover, the data imply that a secondary oxidative stress seems to be a common component of the severe stresses tested.

Dataset Information

In vivo mutational analysis of YtvA from Bacillus subtilis: mechanism of light activation of the general stress response.

Publications

In vivo mutational analysis of YtvA from Bacillus subtilis: mechanism of light activation of the general stress response.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets