Carnahan Robert H, Gould Kathleen L
Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
J Cell Biol. 2003 Sep 1;162(5):851-62. doi: 10.1083/jcb.200305012. Epub 2003 Aug 25.
Cytokinetic actin ring (CAR) formation in Schizosaccharomyces pombe requires two independent actin nucleation pathways, one dependent on the Arp2/3 complex and another involving the formin Cdc12p. Here we investigate the role of the S. pombe Cdc15 homology family protein, Cdc15p, in CAR assembly and find that it interacts with proteins from both of these nucleation pathways. Cdc15p binds directly to the Arp2/3 complex activator Myo1p, which likely explains why actin patches and the Arp2/3 complex fail to be medially recruited during mitosis in cdc15 mutants. Cdc15p also binds directly to Cdc12p. Cdc15p and Cdc12p not only display mutual dependence for CAR localization, but also exist together in a ring-nucleating structure before CAR formation. The disruption of these interactions in cdc15 null cells is likely to be the reason for their complete lack of CARs. We propose a model in which Cdc15p plays a critical role in recruiting and coordinating the pathways essential for the assembly of medially located F-actin filaments and construction of the CAR.
裂殖酵母中的细胞分裂肌动蛋白环（CAR）形成需要两条独立的肌动蛋白成核途径，一条依赖于Arp2/3复合体，另一条涉及formin蛋白Cdc12p。在这里，我们研究了裂殖酵母Cdc15同源家族蛋白Cdc15p在CAR组装中的作用，发现它与这两条成核途径中的蛋白质相互作用。Cdc15p直接与Arp2/3复合体激活剂Myo1p结合，这可能解释了为什么在cdc15突变体的有丝分裂过程中肌动蛋白斑和Arp2/3复合体无法被内侧招募。Cdc15p也直接与Cdc12p结合。Cdc15p和Cdc12p不仅在CAR定位上相互依赖，而且在CAR形成之前就共同存在于一个环成核结构中。cdc15缺失细胞中这些相互作用的破坏可能是它们完全缺乏CAR的原因。我们提出了一个模型，其中Cdc15p在招募和协调内侧定位的F-肌动蛋白丝组装和CAR构建所必需的途径中起关键作用。
