A time-resolved interaction analysis of Bem1 reconstructs the flow of Cdc42 during polar growth
A time-resolved interaction analysis of Bem1 reconstructs the flow of Cdc42 during polar growth
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DOI：
10.26508/lsa.202000813
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发表时间：
2020-09-01
影响因子：
4.4
通讯作者：
Johnsson, Nils
中科院分区：
文献类型：
--
作者：
Grinhagens, Soren;Duenkler, Alexander;Johnsson, Nils
在许多生物体中，Cdc42组织细胞极性并指导细胞结构的形成。通过将Cdc24（活性Cdc42的来源）定位到酵母细胞的生长前端，支架蛋白Bem1有助于形成Cdc42的细胞梯度。这种梯度通过多种效应蛋白的作用指导芽形成、芽生长或细胞分裂。为了解决Bem1如何参与这些转化，我们系统地跟踪了一个细胞周期内的蛋白质相互作用，以定义每个细胞周期阶段Bem1相互作用状态的集合。仅与相互作用伙伴的离散子集相互作用的Bem1突变体允许将特定功能分配给不同的相互作用状态，并确定其细胞分布的决定因素。该分析将Bem1描述为细胞周期特异性穿梭体，可将活性Cdc42从其来源分发到其效应器。这进一步表明，Bem1可能将PAKs cl4和Ste20转化为它们的活性构象。
Cdc42 organizes cellular polarity and directs the formation of cellular structures in many organisms. By locating Cdc24, the source of active Cdc42, to the growing front of the yeast cell, the scaffold protein Bem1, is instrumental in shaping the cellular gradient of Cdc42. This gradient instructs bud formation, bud growth, or cytokinesis through the actions of a diverse set of effector proteins. To address how Bem1 participates in these transformations, we systematically tracked its protein interactions during one cell cycle to define the ensemble of Bem1 interaction states for each cell cycle stage. Mutants of Bem1 that interact with only a discrete subset of the interaction partners allowed to assign specific functions to different interaction states and identified the determinants for their cellular distributions. The analysis characterizes Bem1 as a cell cycle-specific shuttle that distributes active Cdc42 from its source to its effectors. It further suggests that Bem1 might convert the PAKs Cla4 and Ste20 into their active conformations.