Molecular characterization of the growth phase-dependent expression of the lsrA gene, encoding levansucrase of Rahnella aquatilis.
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).
Seo
Jeong-Woo
JW
Korea Research Institute of Bioscience and Biotechnology (KRIBB), 51 Oun-dong, Yusong, Daejon 305-333, Korea.
Jang
Ki-Hyo
KH
Kang
Soon Ah
SA
Song
Ki-Bang
KB
Jang
Eun Kyung
EK
Park
Buem-Seek
BS
Kim
Chul Ho
CH
Rhee
Sang-Ki
SK
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
D004269:DNA, Bacterial; C467896:LsrR protein, Rahnella aquatilis; C467895:LsrS protein, Rahnella aquatilis; D012097:Repressor Proteins; D015534:Trans-Activators; D006602:Hexosyltransferases; C021513:levansucrase