The LuxR homolog ExpR, in combination with the Sin quorum sensing system, plays a central role in Sinorhizobium meliloti gene expression.
Quorum sensing, a population density-dependent mechanism for bacterial communication and gene regulation, plays a crucial role in the symbiosis between alfalfa and its symbiont Sinorhizobium meliloti. The Sin system, one of three quorum sensing systems present in S. meliloti, controls the production of the symbiotically active exopolysaccharide EPS II. Based on DNA microarray data, the Sin system also seems to regulate a multitude of S. meliloti genes, including genes that participate in low-molecular-weight succinoglycan production, motility, and chemotaxis, as well as other cellular processes. Most of the regulation by the Sin system is dependent on the presence of the ExpR regulator, a LuxR homolog. Gene expression profiling data indicate that ExpR participates in additional cellular processes that include nitrogen fixation, metabolism, and metal transport. Based on our microarray analysis we propose a model for the regulation of gene expression by the Sin/ExpR quorum sensing system and another possible quorum sensing system(s) in S. meliloti.
Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, 75083-0688, USA.
Hanh H
HH
Hoang
Anke
A
Becker
Juan E
JE
González
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000378:metabolism*; D002633:Chemotaxis / Q000235:genetics; D004734:Energy Metabolism / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D000455:Medicago sativa / Q000382:microbiology; D008670:Metals / Q000378:metabolism; D009068:Movement; D009586:Nitrogen Fixation / Q000235:genetics; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics; D017385:Sequence Homology; D016962:Sinorhizobium meliloti / Q000235:genetics* / Q000502:physiology; D013559:Symbiosis; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; C083492:EPSI polysaccharide; D008670:Metals; D011135:Polysaccharides, Bacterial; D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins; C076733:FlaD protein, Bacteria; C056779:succinoglycan