Three-dimensional solution structure of PsaE from the cyanobacterium Synechococcus sp. strain PCC 7002, a photosystem I protein that shows structural homology with SH3 domains.
Three-dimensional solution structure of PsaE from the cyanobacterium Synechococcus sp. strain PCC 7002, a photosystem I protein that shows structural homology with SH3 domains.
复制标题
蓝藻聚球藻 PsaE 的三维溶液结构。
DOI：
10.1021/bi00186a004
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Lecomte,JT
中科院分区：
文献类型：
--
作者：
Falzone,CJ;Kao,YH;Zhao,J;Bryant,DA;Lecomte,JT
摘要：PsaE是来自光系统I的69个氨基酸的多肽，存在于类囊体膜的基质侧。蓝细菌聚球藻属菌株PCC 7002的这种蛋白质的三维溶液结构，确定在pH 5.8和室温下使用来自二维和三维NMR实验的900多个实验限制。该结构由具有（+1，+1，+1，-4x）拓扑结构的明确定义的五链/3片层组成。除了在/3D和/3E链之间的310螺旋的单圈之外，没有螺旋区域。PsaE还表现出跨越残基42-56的大的无限制环。与已知蛋白质结构的比较显示与Src同源性3（SH 3）结构域的相似性，Src同源性3（SH 3）结构域是真核生物中参与信号转导的膜相关蛋白。这种匹配是显著的，因为PsaE的47个α-碳可以叠加到来自鸡脑α-血影蛋白的SH 3结构域的α-碳上，均方根偏差为2.3A。虽然两种蛋白质的氨基酸序列具有低的同一性并且环不同，但是β-折叠和310转角的拓扑结构是保守的。来自其他来源的SH 3结构域显示出类似的结构同源性。PsaE的结构被用来阐明其在光系统I中的作用。高等植物、真核藻类和原核蓝藻的光系统I（PS I）1反应中心充当光驱动的氧化还原酶。PS I利用单个红光子的能量（1.8eV）来驱动氧化的铁氧还蛋白的能量上不利的还原（Em= 1.2eV）。
Revised Manuscript Received March 9, 1994® abstract: PsaE is a 69 amino acid polypeptide from photosystem I present on the stromal side of the thylakoid membrane. The three-dimensional solution structure of this protein from the cyanobacterium Synechococcus sp. strain PCC7002 was determined at pH 5.8 and room temperature using over 900 experimental restraints derived from two-and three-dimensional NMR experiments. The structure is comprised of a well-defined five-stranded/3-sheet with (+ 1,+ 1,+ 1,-4x) topology. There is no helical region except for a single turn of 3i0 helix between the/3D and/3E strands. PsaE also exhibits a large unrestrained loop spanning residues 42-56. A comparison to known protein structures revealed similarity with the Src homology 3 (SH3) domain, a membrane-associated protein involved in signal transduction in eukaryotes. The match is remarkable as 47 of the a-carbons of PsaE can be superimposed onto those of the SH3 domainfrom chicken brain a-spectrin with a root-mean-square deviation of 2.3 A. Although the amino acid sequences have low identity and the loops are different in both proteins, the topology of the/3-sheet andthe 3i0 turn is conserved. SH3 domains from other sources show a similar structural homology. The structure of PsaE was used to suggest approaches for elucidating its roles within photosystem I.The photosystem I (PS I) 1 reaction center of higher plants, eukaryotic algae, and the prokaryotic cyanobacteria acts as a light-driven oxidoreductase. PS I utilizes the energy of a single red photon (1.8 eV) to drive the energetically unfavorable reduction of oxidized ferredoxin (Em=