The key Sinorhizobium meliloti succinoglycan biosynthesis gene exoY is expressed from two promoters.
Bacterial exopolysaccharide, succinoglycan, plays an important role in eliciting infection thread formation, which is a key step in the establishment of Sinorhizobium meliloti-alfalfa (Medicago sativa) nitrogen fixing symbiosis. To understand the regulatory mechanisms that control production of succinoglycan, the expression of the key succinoglycan biosynthesis gene, exoY, was analyzed by constructing a set of nested deletions of the exoY promoter region. Two exoY promoters were identified based on the promoter activities and confirmed by direct detection of the transcripts. The expression from both promoters was induced in the exoR95 and exoS96 mutant backgrounds suggesting that both promoters are regulated by the ExoR protein and the ExoS/ChvI two-component signal transduction system. The identification of the exoY promoters provides additional avenue for further analysis of the role of succinoglycan in S. meliloti-alfalfa symbiosis.
Cheng
Hai-Ping
HP
Biological Sciences Department, Lehman College, the City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA. haiping@lehman.cuny.edu
Yao
Shi-Yi
SY
D001426:Bacterial Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005964:Glucosyltransferases / Q000235:genetics*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D011401:Promoter Regions, Genetic; D016962:Sinorhizobium meliloti / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; C056779:succinoglycan; C111504:ExoY protein, bacteria; D005964:Glucosyltransferases