title: Cell envelope stress response in Bacillus licheniformis: integrating comparative genomics, transcriptional profiling, and regulon mining to decipher a complex regulatory network.
abstract: The envelope is an essential structure of the bacterial cell, and maintaining its integrity is a prerequisite for survival. To ensure proper function, transmembrane signal-transducing systems, such as two-component systems (TCS) and extracytoplasmic function (ECF) sigma factors, closely monitor its condition and respond to harmful perturbations. Both systems consist of a transmembrane sensor protein (histidine kinase or anti-sigma factor, respectively) and a corresponding cytoplasmic transcriptional regulator (response regulator or sigma factor, respectively) that mediates the cellular response through differential gene expression. The regulatory network of the cell envelope stress response is well studied in the gram-positive model organism Bacillus subtilis. It consists of at least two ECF sigma factors and four two-component systems. In this study, we describe the corresponding network in a close relative, Bacillus licheniformis. Based on sequence homology, domain architecture, and genomic context, we identified five TCS and eight ECF sigma factors as potential candidate regulatory systems mediating cell envelope stress response in this organism. We characterized the corresponding regulatory network by comparative transcriptomics and regulon mining as an initial screening tool. Subsequent in-depth transcriptional profiling was applied to define the inducer specificity of each identified cell envelope stress sensor. A total of three TCS and seven ECF sigma factors were shown to be induced by cell envelope stress in B. licheniformis. We noted a number of significant differences, indicative of a regulatory divergence between the two Bacillus species, in addition to the expected overlap in the respective responses.
authors.affiliation: Department of General Microbiology, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Wecke
authors.forename: Birgit
authors.initials: B
authors.lastname: Veith
authors.forename: Armin
authors.initials: A
authors.lastname: Ehrenreich
authors.forename: Thorsten
authors.initials: T
authors.lastname: Mascher
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001407:Bacillus / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D002473:Cell Wall / Q000502:physiology*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D023281:Genomics; D000071677:Histidine Kinase; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011494:Protein Kinases / Q000235:genetics; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D018085:Regulon; D012808:Sigma Factor / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012808:Sigma Factor; D011494:Protein Kinases; D000071677:Histidine Kinase