The Caenorhabditis elegans septin complex is nonpolar
The Caenorhabditis elegans septin complex is nonpolar
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DOI：
10.1038/sj.emboj.7601775
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发表时间：
2007-07-25
期刊：
影响因子：
11.4
通讯作者：
Steinmetz, Michel O.
中科院分区：
文献类型：
--
作者：
John, Corinne M.;Hite, Richard K.;Steinmetz, Michel O.
间隔蛋白是保守的GTP酶，其形成异源多聚体复合物并组装成在细胞分裂和极性中起关键作用的细丝。芽殖和裂殖酵母的结果表明，septin复合物围绕四聚体核心形成。然而，核心的分子结构及其对septin复合物和细丝的极性的影响是很难定义的。秀丽隐杆线虫的Septin复合物完全由核心Septin-59和Septin-61形成。我们发现，ESTA-59和ESTA-61形成卷曲螺旋介导的异二聚体的二聚体。通过电子显微镜，这种异源四聚体表现为四种密度的线性排列，代表四个septin亚基。将GFP融合到Septin-59和Septin-61的N末端以及随后的电子显微镜可视化表明Septin亚基的序列是Septin-59/Septin-61/Septin-61/Septin-59。与C-末端卷曲螺旋末端融合的GFP延伸的可视化表明这些从异源四聚体核心横向延伸。总之，我们的研究确立了septin核心复合物是对称的，并表明septins形成非极性细丝。
Septins are conserved GTPases that form heteromultimeric complexes and assemble into filaments that play a critical role in cell division and polarity. Results from budding and fission yeast indicate that septin complexes form around a tetrameric core. However, the molecular structure of the core and its influence on the polarity of septin complexes and filaments is poorly defined. The septin complex of the nematode Caenorhabditis elegans is formed entirely by the core septins UNC-59 and UNC-61. We show that UNC-59 and UNC-61 form a dimer of coiled-coil-mediated heterodimers. By electron microscopy, this heterotetramer appears as a linear arrangement of four densities representing the four septin subunits. Fusion of GFP to the N termini of UNC-59 and UNC-61 and subsequent electron microscopic visualization suggests that the sequence of septin subunits is UNC-59/UNC-61/UNC-61/UNC-59. Visualization of GFP extensions fused to the extremity of the C-terminal coiled coils indicates that these extend laterally from the heterotetrameric core. Together, our study establishes that the septin core complex is symmetric, and suggests that septins form nonpolar filaments.