title: A novel role of ImmE7 in the autoregulatory expression of the ColE7 operon and identification of possible RNase active sites in the crystal structure of dimeric ImmE7.
abstract: Site-specific cleavage of mRNA has been identified in vivo for the polycistronic colicin E7 operon (ColE7), which occurs between G and A nucleotides located at the Asp52 codon (GAT) of the immunity gene (ceiE7). In vitro, this specific cleavage occurs only in the presence of the ceiE7 gene product (ImmE7). The crystal structure of dimeric ImmE7 has been determined at 1.8 A resolution by X-ray crystallographic analysis. We found that several residues located at the interface of dimeric ImmE7 bear surprising resemblance to the active sites of some RNases. These results suggest that dimeric ImmE7 may possess a novel RNase activity that cleaves its own mRNA at a specific site and thus autoregulates translational expression of the downstream celE7 gene as well as degradation of the upstream ceaE7 mRNA.
authors.affiliation: Institute of Biochemistry, Center for Cellular and Molecular Biology, National Yang Ming University, Taipei, Taiwan, Republic of China.
authors.forename: S Y
authors.initials: SY
authors.lastname: Hsieh
authors.forename: T P
authors.initials: TP
authors.lastname: Ko
authors.forename: M Y
authors.initials: MY
authors.lastname: Tseng
authors.forename: W
authors.initials: W
authors.lastname: Ku
authors.forename: K F
authors.initials: KF
authors.lastname: Chak
authors.forename: H S
authors.initials: HS
authors.lastname: Yuan
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003087:Colicins; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000235:genetics; D019281:Dimerization; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009876:Operon; D011487:Protein Conformation; D017510:Protein Folding; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003087:Colicins; D017931:DNA Primers; D012329:RNA, Bacterial; D012333:RNA, Messenger; C007104:colicin immunity proteins; D012260:Ribonucleases