title: Enhancement of translation initiation by A/T-rich sequences downstream of the initiation codon in Escherichia coli.
abstract: The region located downstream of the initiation codon constitutes part of the translation initiation signal, significantly affecting the level of protein expression in E. coli. In order to determine its influence on translation initiation, we inserted random 12-base sequences downstream of the initiation codon of the lacZ gene. A total of 119 random clones showing higher beta-galactosidase activities than the control lacZ gene were isolated and subsequently sequenced. Analysis of these clones revealed that their insertion sequences are strikingly rich in A and T, but poor in G, with no consensus sequences among them. Toeprinting experiments and polysome profile analysis confirmed that the A/T-rich sequences enhance translation at the level of initiation. Collectively, the present data demonstrate that A/T richness of the region following the initiation codon plays a significant role in E. coli gene expression.
authors.affiliation: Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ, USA.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Qing
authors.forename: Bing
authors.initials: B
authors.lastname: Xia
authors.forename: Masayori
authors.initials: M
authors.lastname: Inouye
mesh_terms: D020856:AT Rich Sequence; D018387:Codon, Initiator; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D016368:Frameshift Mutation; D015964:Gene Expression Regulation, Bacterial; D007763:Lac Operon; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D020871:RNA Stability; D012329:RNA, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D018387:Codon, Initiator; D004251:DNA Transposable Elements; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001616:beta-Galactosidase