title: Versatility of global transcriptional regulators in alpha-Proteobacteria: from essential cell cycle control to ancillary functions.
abstract: Recent data indicate that cell cycle transcription in many alpha-Proteobacteria is executed by at least three conserved functional modules in which pairs of antagonistic regulators act jointly, rather than in isolation, to control transcription in S-, G2- or G1-phase. Inactivation of module components often results in pleiotropic defects, ranging from cell death and impaired cell division to fairly benign deficiencies in motility. Expression of module components can follow systemic (cell cycle) or external (nutritional/cell density) cues and may be implemented by auto-regulation, ancillary regulators or other (unknown) mechanisms. Here, we highlight the recent progress in understanding the molecular events and the genetic relationships of the module components in environmental, pathogenic and/or symbiotic alpha-proteobacterial genera. Additionally, we take advantage of the recent genome-wide transcriptional analyses performed in the model alpha-Proteobacterium Caulobacter crescentus to illustrate the complexity of the interactions of the global regulators at selected cell cycle-regulated promoters and we detail the consequences of (mis-)expression when the regulators are absent. This review thus provides the first detailed mechanistic framework for understanding orthologous operational principles acting on cell cycle-regulated promoters in other alpha-Proteobacteria.
authors: Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Medicine/CMU, University of Geneva, Rue Michel Servet 1, 1211 Genève 4, Switzerland.
authors: Gaël
authors: G
authors: Panis
authors: Department of Biology, Center for Cancer and Developmental Biology, Interdisciplinary Research Institute for the Sciences, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA.
authors: Sean R
authors: SR
authors: Murray
authors: Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Medicine/CMU, University of Geneva, Rue Michel Servet 1, 1211 Genève 4, Switzerland patrick.viollier@unige.ch.
authors: Patrick H
authors: PH
authors: Viollier
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics* / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic / Q000235:genetics
keywords: Caulobacter crescentus; CcrM methyltransferase; CtrA; GcrA; MucR; SciP; alpha-Proteobacteria; cell cycle transcription; epigenetics; global regulator