Cytokinesis in Arabidopsis: Cytokinetic vesicles, cargo proteins and fusion machinery

在植物细胞质分裂过程中，分配膜是通过分泌囊泡的靶传递到细胞分裂平面，囊泡相互融合形成细胞板而形成的。目前尚不清楚哪些蛋白质被运输，以及它们在细胞质分裂中起什么作用。细胞动力学囊泡携带所谓的SNARE蛋白的顺式复合物，这些复合物被酶解；随后，所谓的SM蛋白介导互补SNARE蛋白的反式复合物的形成，促进相邻囊泡之间的融合。细胞分裂过程中顺式到跨snare复合物重组的调控机制尚不清楚。(1)本研究的一个主要目标是确定通过携带knolle的膜囊泡运送到细胞分裂平面的货物蛋白，并有助于分割膜的形成或成熟和/或形成交叉壁的合成或组装。根据要鉴定的蛋白质的数量，我们将主要把我们的功能分析集中在似乎专门参与细胞质分裂的蛋白质上。(2)另一个目标是鉴定AAA+ atp酶及其α - snap接头在细胞板形成之前参与顺式- snare复合物的分解，并表征它们在细胞分裂中的作用。我们还将讨论SM蛋白KEULE捕获单体Qa-SNARE KNOLLE是否涉及与拆卸机制的直接物理相互作用。(3)第三个目标是分析Qa-SNAREs与SM蛋白在细胞分裂过程中的相互作用，方法是鉴定SM蛋白KEULE与其平行体SEC1B在与KNOLLE相互作用过程中的特异性决定因素，并定义SM相互作用所需的相关KNOLLE序列基序。我们还将确定KEULE和SEC1B与SYP132的相互作用方式是否与KNOLLE相同或不同。

In plant cytokinesis, the partitioning membrane originates through target delivery of secretory vesicles to the cell division plane and the fusion of vesicles with one another, generating the cell plate. It is not known what proteins are transported and what role they play in cytokinesis. The cytokinetic vesicles bear so-called cis-complexes of SNARE proteins, which are enzymatically disassembled; subsequently, so-called SM proteins mediate the formation of trans-complexes of complementary SNARE proteins that facilitate the fusion between adjacent vesicles. Regulatory mechanisms underlying the reorganisation of cis to trans-SNARE complexes in cytokinesis are not known.(1) A major objective of the proposed research is to identify cargo proteins that are delivered on KNOLLE-bearing membrane vesicles to the plane of cell division and contribute to the formation or maturation of the partitioning membrane and/or the synthesis or assembly of the forming cross wall. Depending on the number of proteins to be identified, we will primarily focus our functional analysis on proteins that appear specifically involved in cytokinesis.(2) Another objective is to identify the AAA+ ATPase and its alpha-SNAP adaptor involved in cis-SNARE complex disassembly prior to cell plate formation and to characterise their action in cytokinesis. We will also address whether the capture of monomeric Qa-SNARE KNOLLE by SM protein KEULE involves direct physical interaction with the disassembling machinery.(3) A third objective is to analyse the interaction between Qa-SNAREs and SM proteins in cytokinesis by identifying specificity determinants that distinguish SM protein KEULE from its paralogue SEC1B in interaction with KNOLLE and by defining relevant KNOLLE sequence motifs required for SM interaction. We will also determine whether KEULE and SEC1B interact with SYP132 in the same or a different manner compared to KNOLLE.