Huijbregts Richard P H, Svitin Anton, Stinnett Monica W, Renfrow Matthew B, Chesnokov Igor
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, School of Medicine, Birmingham, AL 35294, USA.
Mol Biol Cell. 2009 Jan;20(1):270-81. doi: 10.1091/mbc.e08-07-0754. Epub 2008 Nov 5.
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.
起源识别复合物（ORC）是一种由六个亚基组成的蛋白质，对DNA复制和其他细胞功能至关重要。Orc6是ORC最小的亚基，对果蝇的复制和胞质分裂都必不可少，并且与septin蛋白Pnut相互作用，Pnut是果蝇septin复合物的一部分。在本研究中，我们描述了对Orc6与Pnut以及整个果蝇septin复合物相互作用的分析。septin复合物从果蝇胚胎中纯化得到，也通过重组蛋白进行了重构。Orc6与septin复合物的相互作用依赖于Pnut的卷曲螺旋结构域。此外，Orc6与Pnut的结合增加了果蝇septin复合物的内在GTP酶活性，而在没有GTP的情况下，它会增强septin复合物丝的形成。这些结果表明Orc6在septin复合物功能中发挥积极作用。Orc6可能是在有丝分裂最后阶段指导胞质分裂机制的控制机制的一部分。
