title: Drosophila Orc6 facilitates GTPase activity and filament formation of the septin complex.
abstract: The origin recognition complex or ORC is a six-subunit protein important for DNA replication and other cell functions. Orc6, the smallest subunit of ORC, is essential for both replication and cytokinesis in Drosophila, and interacts with the septin protein Pnut, which is part of the Drosophila septin complex. In this study, we describe the analysis of the interaction of Orc6 with Pnut and whole Drosophila septin complex. Septin complex was purified from Drosophila embryos and also reconstituted from recombinant proteins. The interaction of Orc6 with the septin complex is dependent on the coiled-coil domain of Pnut. Furthermore, the binding of Orc6 to Pnut increases the intrinsic GTPase activity of the Drosophila septin complex, whereas in the absence of GTP it enhances septin complex filament formation. These results suggest an active role for Orc6 in septin complex function. Orc6 might be a part of a control mechanism directing the cytokinesis machinery during the final steps of mitosis.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, School of Medicine, Birmingham, AL 35294, USA.
authors.forename: Richard P H
authors.initials: RP
authors.lastname: Huijbregts
authors.forename: Anton
authors.initials: A
authors.lastname: Svitin
authors.forename: Monica W
authors.initials: MW
authors.lastname: Stinnett
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Renfrow
authors.forename: Igor
authors.initials: I
authors.lastname: Chesnokov
mesh_terms: D000818:Animals; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D029721:Drosophila Proteins; D008840:Microfilament Proteins; D046912:Multiprotein Complexes; C477598:ORC6 protein, Drosophila; D051738:Origin Recognition Complex; D011993:Recombinant Fusion Proteins; C087195:pnut protein, Drosophila; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases