Molecular Biology of Centrosomes and Cilia Unit, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany.
Mol Biol Cell. 2013 May;24(9):1290-304. doi: 10.1091/mbc.E12-08-0608. Epub 2013 Feb 27.
The conserved NDR-kinase Dbf2 plays a critical role in cytokinesis in budding yeast. Among its cytokinesis-related substrates is the F-BAR protein Hof1. Hof1 colocalizes at the cell division site with the septin complex and, as mitotic exit progresses, moves to the actomyosin ring (AMR). Neither the function of Hof1 at the septin complex nor the mechanism by which Hof1 supports AMR constriction is understood. Here we establish that Dbf2 has a dual function in Hof1 regulation. First, we show that the coiled-coil region, which is adjacent to the conserved F-BAR domain, is required for the binding of Hof1 to septins. The Dbf2-dependent phosphorylation of Hof1 at a single serine residue (serine 313) in this region diminishes the recruitment of Hof1 to septins both in vitro and in vivo. Genetic and functional analysis indicates that the binding of Hof1 to septins is important for septin rearrangement and integrity during cytokinesis. Furthermore, Dbf2 phosphorylation of Hof1 at serines 533 and 563 promotes AMR constriction most likely by inhibiting the SH3-domain-dependent interactions of Hof1. Thus our data show that Dbf2 coordinates septin and AMR functions during cytokinesis through the regulation/control of Hof1.
在芽殖酵母中，保守的 NDR-激酶 Dbf2 在胞质分裂中起着关键作用。其细胞分裂相关底物之一是 F-BAR 蛋白 Hof1。Hof1 与隔膜复合物在细胞分裂部位共定位，随着有丝分裂退出的进展，它移动到肌动球蛋白环（AMR）。Hof1 在隔膜复合物上的功能以及 Hof1 支持 AMR 收缩的机制尚不清楚。在这里，我们确定了 Dbf2 在 Hof1 调节中的双重功能。首先，我们表明，紧邻保守的 F-BAR 结构域的卷曲螺旋区对于 Hof1 与隔膜的结合是必需的。该区域中单个丝氨酸残基（丝氨酸 313）上的 Dbf2 依赖性 Hof1 磷酸化，无论是在体外还是体内，都会减少 Hof1 向隔膜的募集。遗传和功能分析表明，Hof1 与隔膜的结合对于隔膜在胞质分裂过程中的重排和完整性很重要。此外，Dbf2 在 Hof1 的丝氨酸 533 和 563 上的磷酸化作用最有可能通过抑制 Hof1 的 SH3 结构域依赖性相互作用来促进 AMR 收缩。因此，我们的数据表明，Dbf2 通过调节/控制 Hof1 来协调胞质分裂过程中的隔膜和 AMR 功能。
