Allophycocyanin and phycocyanin crystal structures reveal facets of phycobilisome assembly
Allophycocyanin and phycocyanin crystal structures reveal facets of phycobilisome assembly
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DOI：
10.1016/j.bbabio.2012.11.006
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发表时间：
2013-03-01
影响因子：
4.3
通讯作者：
Adir, Noam
中科院分区：
文献类型：
--
作者：
Marx, Ailie;Adir, Noam
藻胆体的分离的藻胆蛋白组分的X射线晶体结构提供了高分辨率的细节，以不同水平的复杂性和细节描述这种捕光复合物。在蛋白质数据库中可获得的几乎所有藻蓝蛋白（PC）和别藻蓝蛋白（APC）结构中，都观察到了在先前确定结构的晶格中三聚体不依赖于接头组装成六聚体。本文报道了细长聚球藻7942的PC和APC、聚胞藻6803的PC和硫化热聚球藻的PC在尿素存在下结晶的X射线晶体结构。所有五种结构在亚基、单体和三聚体水平上与其他PC和APC结构高度相似。聚球藻APC形成独特的松散六聚体，其可显示核心组装和杆连接的结构要求。虽然聚球藻PC组装成典型的六聚体，但它不会进一步组装成杆状。与大多数PC结构不同，集胞藻PC不能形成六聚体。向T vulcanus PC中添加低浓度的尿素抑制该蛋白质形成六聚体的倾向，导致由三聚体组成的晶格。讨论了这些组装差异的分子来源及其与藻胆体结构的相关性。(C)2012爱思唯尔有限公司版权所有。
X-ray crystal structures of the isolated phycobiliprotein components of the phycobilisome have provided high resolution details to the description of this light harvesting complex at different levels of complexity and detail. The linker-independent assembly of trimers into hexamers in crystal lattices of previously determined structures has been observed in almost all of the phycocyanin (PC) and allophycocyanin (APC) structures available in the Protein Data Bank. In this paper we describe the X-ray crystal structures of PC and APC from Synechococcus elongatus sp. PCC 7942, PC from Synechocystis sp. PCC 6803 and PC from Thermosynechococcus vulcanus crystallized in the presence of urea. All five structures are highly similar to other PC and APC structures on the levels of subunits, monomers and trimers. The Synechococcus APC forms a unique loose hexamer that may show the structural requirements for core assembly and rod attachment. While the Synechococcus PC assembles into the canonical hexamer, it does not further assemble into rods. Unlike most PC structures, the Synechocystis PC fails to form hexamers. Addition of low concentrations of urea to T vulcanus PC inhibits this proteins propensity to form hexamers, resulting in a crystal lattice composed of trimers. The molecular source of these differences in assembly and their relevance to the phycobilisome structure is discussed. (C) 2012 Elsevier B.V. All rights reserved.