Septins and the Cell Cycle in Budding Yeast

描述（由申请人提供）：发现了Septins作为芽殖酵母细胞分裂缺陷突变体。隔片形成花丝，并在母体和芽之间的颈部形成一个环。间隔蛋白作为母/芽极性的扩散屏障和作为调节蛋白的支架。我们建议研究septin的结构，组装和功能的芽殖酵母。 隔环内有细丝，薄切片电镜可见，旋转阴影标本可见。环通过细胞周期改变其形状和大小，并且具有极性。我们将通过细胞周期研究纤维和环结构，以及它们组装和拆卸的分子机制，使用体内和体外方法。 纺锤体位置检查点确保有丝分裂纺锤体在退出有丝分裂发生之前移动到母/芽颈中，随后是细胞分裂。有丝分裂出口由G蛋白Teml控制，Teml与仅在芽中发现的GEF Lte 1相互作用。我们发现septin突变体缺陷的限制Lte 1的芽，与septins的扩散屏障作用一致。我们将研究这种效应的分子机制。 纺锤体位置检查点似乎也涉及细胞质微管与颈部推定的传感器蛋白的相互作用。根据我们发表的研究，我们假设隔蛋白环作为传感器的支架。为了验证这一假设，我们确定了新的突变缺陷的纺锤体位置检查点，我们将研究这些基因如何有助于纺锤体位置检查点的分子机制。 在芽形态发生检查点，结构的隔蛋白被假设为传感机制。为了验证这一假设，我们将检查septin丝结构与细胞周期和检查点激活。

DESCRIPTION (provided by applicant): Septins were discovered as mutants defective in cell division in budding yeast. Septins form filaments and compose a ring at the neck between mother and bud. Septins function as a diffusion barrier for mother / bud polarity and as a scaffold for regulatory proteins. We propose to study septin structure, assembly, and function in budding yeast. The septin ring contains filaments, seen by thin section EM and now in rotary shadowed preparations. The ring changes its shape and size through the cell cycle, and it has polarity. We will investigate filament and ring structure through the cell cycle, and the molecular mechanisms of their assembly and disassembly, using in vivo and in vitro approaches. The spindle position checkpoint ensures that the mitotic spindle moves into the mother / bud neck before exit from mitosis occurs, followed by cell division. Mitotic exit is controlled by the G-protein, Teml, which interacts with a GEF, Lte1, found only in the bud. We discovered septin mutants defective in restriction of Lte1 to the bud, consistent with a diffusion barrier role for septins. We will investigate the molecular mechanism of this effect. The spindle position checkpoint also appears to involve the interaction of cytoplasmic microtubules with a putative sensor protein at the neck. We hypothesize that the septin ring serves as the scaffold for the sensor, based on our published studies. To test this hypothesis, we identified new mutants defective in the spindle position checkpoint, and we will study how these genes contribute to the molecular mechanism of the spindle position checkpoint. In the bud morphogenesis checkpoint, the architecture of the septins is hypothesized to be the sensing mechanism. To test this hypothesis, we will examine septin filament architecture with respect to the cell cycle and checkpoint activation.