Functional insight into the role of Orc6 in septin complex filament formation in Drosophila.
Functional insight into the role of Orc6 in septin complex filament formation in Drosophila.
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DOI：
10.1091/mbc.e14-02-0734
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发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Chesnokov I
中科院分区：
文献类型：
--
作者：
Akhmetova K;Balasov M;Huijbregts RP;Chesnokov I
详细的作用，保守的septin基序，GTP，和Orc 6在果蝇septin复合物的功能进行检查，在体外和体内的活动物。提出了Orc 6调节隔蛋白丝形成的新机制。Septins属于聚合GTP结合蛋白的家族，其对于胞质分裂和涉及细胞皮层的空间组织的其他过程是重要的。我们重建了一个重组果蝇septin复合物，并比较了野生型和几个突变septin复合物的变体在体外和体内的活动。我们发现，果蝇septin复合物的功能依赖于完整的GTP结合和/或水解结构域的Pnut，Sep 1，Sep 2。septins的功能性C-末端结构域的存在是复合物的完整性所必需的。果蝇Orc 6蛋白是起源识别复合物（origin recognition complex，ORC）的最小亚基，直接与septin复合物结合，促进septin丝的形成。Orc 6通过其N-末端TFIIB样结构域的相互作用形成二聚体。该蛋白的这种能力表明Orc 6在果蝇中刺激Septin聚合中的直接桥接作用。这里报道的研究提供了一个果蝇septin复合物的功能解剖，并强调后生动物septin复合物之间的基本保守和分歧的功能。
Detailed roles of conserved septin motifs, GTP, and Orc6 in Drosophila septin complex functions are examined both in vitro and in vivo in a live animal. A novel mechanism of Orc6 regulation of septin filament formation is presented. Septins belong to a family of polymerizing GTP-binding proteins that are important for cytokinesis and other processes that involve spatial organization of the cell cortex. We reconstituted a recombinant Drosophila septin complex and compared activities of the wild-type and several mutant septin complex variants both in vitro and in vivo. We show that Drosophila septin complex functions depend on the intact GTP-binding and/or hydrolysis domains of Pnut, Sep1, and Sep2. The presence of the functional C-terminal domain of septins is required for the integrity of the complex. Drosophila Orc6 protein, the smallest subunit of the origin recognition complex (ORC), directly binds to septin complex and facilitates septin filament formation. Orc6 forms dimers through the interactions of its N-terminal, TFIIB-like domains. This ability of the protein suggests a direct bridging role for Orc6 in stimulating septin polymerization in Drosophila. Studies reported here provide a functional dissection of a Drosophila septin complex and highlight the basic conserved and divergent features among metazoan septin complexes.