Regulation of exopolysaccharide production in Rhizobium leguminosarum biovar viciae WSM710 involves exoR

摘要: A mildly acid-sensitive mutant of Rhizobium leguminosarum bv. viciae WSM710 (WR6-35) produced colonies which were more mucoid in phenotype than the wild-type. Strain WR6-35 contained a single copy Tn5 and observed phenotype, acid sensitivity Tn5-induced kanamycin resistance 100% co-transducible using phage RL38. threefold exopolysaccharide (EPS) wild-type minimal medium devoid nitrogen source. EPS by was identical as determined proton NMR spectra. An EcoRI rhizobial fragment containing flanking sequences cloned from mutant, restriction mapped sequenced. There extensive similarity between ORF disrupted R. exoR gene (Sinorhizobium) meliloti Rm1021 (71.3% identity over 892 bp). At protein level there 70% 93.3% 267 amino acids with ExoR Rm1021. Hydrophilicity profiles two proteins these rhizobia are superimposable. This thus designated exoR. The data suggest that has regulatory encoding negatively modulates biosynthesis WSM710. Despite earlier suggestions production tolerance might be positively correlated, disruption either or its associated overproduction does not result acid-tolerant when cultures screened on conventional laboratory agar.