title: Crystal structure of the bacterial conjugation repressor finO.
abstract: The conjugative transfer of F-like plasmids is repressed by FinO, an RNA binding protein. FinO interacts with the F-plasmid encoded traJ mRNA and its antisense RNA, FinP, stabilizing FinP against endonucleolytic degradation and facilitating sense-antisense RNA recognition. Here we present the 2.0 A resolution X-ray crystal structure of FinO, lacking its flexible N-terminal extension. FinO adopts a novel, elongated, largely helical conformation. An N-terminal region, previously shown to contact RNA, forms a positively charged alpha-helix (helix 1) that protrudes 45 A from the central core of FinO. A C-terminal region of FinO that is implicated in RNA interactions also extends out from the central body of the protein, adopting a helical conformation and packing against the base of the N-terminal helix. A highly positively charged patch on the surface of the FinO core may present another RNA binding surface. The results of an in vitro RNA duplexing assay demonstrate that the flexible N-terminal region of FinO plays a key role in FinP-traJ RNA recognition, and supports our proposal that this region and the N-terminus of helix 1 interact with and stabilize paired, complementary RNA loops in a kissing complex.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.
authors.forename: A F
authors.initials: AF
authors.lastname: Ghetu
authors.forename: M J
authors.initials: MJ
authors.lastname: Gubbins
authors.forename: L S
authors.initials: LS
authors.lastname: Frost
authors.forename: J N
authors.initials: JN
authors.lastname: Glover
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D003227:Conjugation, Genetic / Q000235:genetics*; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D018583:Pliability; D011485:Protein Binding; D017433:Protein Structure, Secondary; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D055672:Static Electricity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D010446:Peptide Fragments; D016372:RNA, Antisense; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C488999:TraJ protein, E coli; C041427:TraJ protein, bacteria; C074275:FinO protein, E coli