Nucleus-Encoded Protein BFA1 Promotes Efficient Assembly of the Chloroplast ATP Synthase Coupling Factor 1
Nucleus-Encoded Protein BFA1 Promotes Efficient Assembly of the Chloroplast ATP Synthase Coupling Factor 1
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DOI：
10.1105/tpc.18.00075
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发表时间：
2018-07
期刊：
影响因子：
11.6
通讯作者：
Lin Zhang;H. Pu;Zhikun Duan;Yonghong Li;Bei Liu;Qiqi Zhang;Wenjing Li;J. Rochaix;Lin Liu-Lin
中科院分区：
文献类型：
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作者：
Lin Zhang;H. Pu;Zhikun Duan;Yonghong Li;Bei Liu;Qiqi Zhang;Wenjing Li;J. Rochaix;Lin Liu-Lin
叶绿体蛋白BFA1主要由两个β-桶组成，并通过与CF1β、γ和ε亚基的特异性相互作用，作为CF1组装途径的早期步骤的伴侣。f型ATP合成酶产生细胞中几乎所有的ATP。催化模块F1通常包括一个围绕γ/ε柄的α3β3六聚体。然而，目前还不清楚这些亚基是如何组装形成催化马达的。在这项工作中，我们鉴定并表征了一种叶绿体蛋白，该蛋白与叶绿体ATP合成酶的CF1β， γ和ε亚基相互作用，并且是其F1模块组装所必需的。我们将该蛋白命名为ATP SYNTHASE1 （BFA1）所需的BIOGENESIS FACTOR，并以2.8-Å分辨率测定了其晶体结构。BFA1主要由两个相互作用的β-桶组成，它们几乎垂直于彼此。通过酵母双杂交实验进一步确定了BFA1与CF1β和γ亚基的接触区域。通过分子对接分析，发现BFA1和CF1β/γ之间存在紧密的拟合接触位点，没有空间冲突。我们提出BFA1主要作为支架蛋白促进CF1α/β异源二聚体与CF1γ的结合。随后其他CF1α/β异源二聚体的组装可能会改变CF1γ亚基的位置，从而完成CF1模块的组装。这种CF1组装过程可能适用于其他f型ATP合酶，因为它们的结构高度保守。
Chloroplast protein BFA1 is comprised primarily of two β-barrels and acts as a chaperone orchestrating the early steps of the CF1 assembly pathway via specific interaction with the CF1β, γ, and ε subunits. F-type ATP synthases produce nearly all of the ATP found in cells. The catalytic module F1 commonly comprises an α3β3 hexamer surrounding a γ/ε stalk. However, it is unclear how these subunits assemble to form a catalytic motor. In this work, we identified and characterized a chloroplast protein that interacts with the CF1β, γ, and ε subunits of the chloroplast ATP synthase and is required for assembly of its F1 module. We named this protein BIOGENESIS FACTOR REQUIRED FOR ATP SYNTHASE1 (BFA1) and determined its crystal structure at 2.8-Å resolution. BFA1 is comprised primarily of two interacting β-barrels that are oriented nearly perpendicularly to each other. The contact region between BFA1 and the CF1β and γ subunits was further mapped by yeast two-hybrid assays. An in silico molecular docking analysis was performed and revealed close fitting contact sites without steric conflicts between BFA1 and CF1β/γ. We propose that BFA1 acts mainly as a scaffold protein promoting the association of a CF1α/β heterodimer with CF1γ. The subsequent assembly of other CF1α/β heterodimers may shift the position of the CF1γ subunit to complete assembly of the CF1 module. This CF1 assembly process is likely to be valid for other F-type ATP synthases, as their structures are highly conserved.