α-Helical Domains Affecting the Oligomerization of Vipp1 and Its Interaction with Hsp70/DnaK in Chlamydomonas
α-Helical Domains Affecting the Oligomerization of Vipp1 and Its Interaction with Hsp70/DnaK in Chlamydomonas
复制标题
影响衣藻中 Vipp1 寡聚化及其与 Hsp70/DnaK 相互作用的 α 螺旋结构域。
DOI：
10.1021/acs.biochem.5b00050
复制
发表时间：
2015-08-11
期刊：
影响因子：
2.9
通讯作者：
Liu, Cuimin
中科院分区：
文献类型：
--
作者：
Gao, Fei;Wang, Wenyan;Liu, Cuimin
质体1中的囊泡诱导蛋白（Vipp1）在叶绿体中形成bbb1mda有序同源寡聚复合物，并参与光合机制的生物发生。Hsp70伴侣系统已被证明与Vipp1相互作用，影响其高阶结构。本研究利用reinhardii衣藻Vipp1 （CrVipp1）的一系列缺失突变体来研究α -螺旋结构域（H1-H7）在介导其结构和与Hsp70同源物DnaK相互作用中的作用。这些分析结果表明，CrVipp1的α -螺旋结构域H1-H6是其在蛋白酶抗性大复合物（称为超低聚物）中有效积累所必需的。这些α -螺旋结构域的缺失，无论是单独的还是组合的，都会导致CrVipp1组装成更小的、蛋白酶敏感的低聚物的异质混合物。此外，结构域H2和H3需要在突变寡聚物中形成稳定的结构核心，而结构域H1和H4-H6可能在超寡聚物组装的下游发挥作用。DnaK只能弱地与任何形式的CrVipp1结合，这些CrVipp1可以有效地组装成超低聚物。相比之下，某些错误折叠的CrVipp1寡聚物在其H4和H7结构域介导的过程中与DnaK的相互作用更为强烈。在CrVipp1生物合成的早期阶段，DnaK也与全长CrVipp1相互作用，可能在寡聚化途径的初始阶段。综上所述，这些数据表明，不仅α -螺旋结构域，而且CrVipp1的寡聚态也会影响其与DnaK的相互作用。因此，Hsp70/DnaK系统可能参与了Vipp1超低聚物的组装。
Vesicle-inducing protein in plastids 1 (Vipp1) forms >1 MDa ordered homo-oligomeric complexes in chloroplasts and is involved in the biogenesis of photosynthetic machinery. The Hsp70 chaperone system has been shown to interact with Vipp1, influencing its higher-order structure. In this study, a series of deletion mutants in Chlamydomonas reinhardii Vipp1 (CrVipp1) is used to investigate the role of the alpha-helical domains (H1-H7) in mediating its structure and interaction with DnaK, an Hsp70 orthologue. Results from these analyses demonstrate that alpha-helical domains H1-H6 of CrVipp1 are required for its efficient accumulation in protease-resistant large complexes, termed super-oligomers. Deletions of these alpha-helical domains, either individually or in combination, cause CrVipp1 to assemble into a heterogeneous mixture of smaller, protease-sensitive oligomers. Furthermore, domains H2 and H3 are required to form a stable structural core in mutant oligomers, whereas domains H1 and H4-H6 likely function downstream in assembly of the superoligomer. DnaK binds only weakly to any form of CrVipp1 that efficiently assembles into superoligomers. In contrast, the interaction with DnaK is much more robust with certain misfolded CrVipp1 oligomers in a process mediated by their H4 and H7 domains. DnaK also interacts with full-length CrVipp1 at an early stage of CrVipp1 biosynthesis, perhaps during initial steps in the oligomerization pathway. Taken together, these data suggest that not only alpha-helical domains but also the oligomeric states of CrVipp1 influence its interaction with DnaK. It is therefore plausible that the Hsp70/DnaK system may be involved in the assembly of Vipp1 superoligomers.