title: Molecular characterization of the growth phase-dependent expression of the lsrA gene, encoding levansucrase of Rahnella aquatilis.
abstract: Expression of the lsrA gene from Rahnella aquatilis, encoding levansucrase, is tightly regulated by the growth phase of the host cell; low-level expression was observed in the early phase of cell growth, but expression was significantly stimulated in the late phase. Northern blot analysis revealed that regulation occurred at the level of transcription. The promoter region was identified by primer extension analysis. Two opposite genetic elements that participate in the regulation of lsrA expression were identified upstream of the lsrA gene: the lsrS gene and the lsrR region. The lsrS gene encodes a protein consisting of 70 amino acid residues (M(r), 8,075), which positively activated lsrA expression approximately 20-fold in a growth phase-dependent fashion. The cis-acting lsrR region, which repressed lsrA expression about 10-fold, was further narrowed to two DNA regions by deletion analysis. The concerted action of two opposite regulatory functions resulted in the growth phase-dependent activation of gene expression in Escherichia coli independent of the stationary sigma factor sigma(S).
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology (KRIBB), 51 Oun-dong, Yusong, Daejon 305-333, Korea.
authors.forename: Jeong-Woo
authors.initials: JW
authors.lastname: Seo
authors.forename: Ki-Hyo
authors.initials: KH
authors.lastname: Jang
authors.forename: Soon Ah
authors.initials: SA
authors.lastname: Kang
authors.forename: Ki-Bang
authors.initials: KB
authors.lastname: Song
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Jang
authors.forename: Buem-Seek
authors.initials: BS
authors.lastname: Park
authors.forename: Chul Ho
authors.initials: CH
authors.lastname: Kim
authors.forename: Sang-Ki
authors.initials: SK
authors.lastname: Rhee
mesh_terms: D000595:Amino Acid Sequence; D017901:Bacteriophage P2; D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D006602:Hexosyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D020638:Rahnella / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site
chemical_list: D004269:DNA, Bacterial; C467896:LsrR protein, Rahnella aquatilis; C467895:LsrS protein, Rahnella aquatilis; D012097:Repressor Proteins; D015534:Trans-Activators; D006602:Hexosyltransferases; C021513:levansucrase