The 2 Å resolution crystal structure of HetL, a pentapeptide repeat protein involved in regulation of heterocyst differentiation in the cyanobacterium Nostoc sp strain PCC 7120
The 2 Å resolution crystal structure of HetL, a pentapeptide repeat protein involved in regulation of heterocyst differentiation in the cyanobacterium Nostoc sp strain PCC 7120
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DOI：
10.1016/j.jsb.2008.09.010
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发表时间：
2009-01-01
影响因子：
3
通讯作者：
Kennedy, Michael A.
中科院分区：
文献类型：
--
作者：
Ni, Shuisong;Sheldrick, George M.;Kennedy, Michael A.
蓝细菌Nostoc sp. PCC 7120的hetL基因编码237个氨基酸的蛋白质（25.6kDa），其含有40个预测的串联五肽重复。Nostoc sp. PCC 7120是一种丝状蓝细菌，其形成异形胞，在其水性环境中氮饥饿期间能够固定大气N-2的特化细胞。在这些条件下，异形胞以大约每10-15个营养细胞中有一个的规则模式出现。异形胞分化受到数百个基因的高度调控，其中一个基因编码PatS，PatS被认为是通过发育异形胞来抑制邻近营养细胞中异形胞分化的细胞间肽信号，从而有助于异形胞沿着细丝的图案形成和间隔。虽然PatS的过表达抑制念珠藻属PCC 7120中的异形胞分化，但HetL的过表达产生多个连续异形胞表型，并丧失野生型异形胞模式，并且含有额外拷贝的hetL的菌株即使在过表达PatS的细胞中也允许异形胞形成。因此，HetL似乎干扰异型胞分化抑制PatS，然而，HetL功能的机制仍然未知。作为探索其生物化学功能机制的第一步，HetL的晶体结构已经使用硫异常散射在2.0埃分辨率下得到解决。(C)2008年由Elsevier Inc.出版
The hetL gene from the cyanobacterium Nostoc sp. PCC 7120 encodes a 237 amino acid protein (25.6 kDa) containing 40 predicted tandem pentapeptide repeats. Nostoc sp. PCC 7120 is a filamentous cyanobacterium that forms heterocysts, specialized cells capable of fixing atmospheric N-2 during nitrogen starvation in its aqueous environment. Under these conditions, heterocysts occur in a regular pattern of approximately one out of every 10-15 vegetative cells. Heterocyst differentiation is highly regulated involving hundreds of genes, one of which encodes PatS, thought to be an intercellular peptide signal made by developing heterocysts to inhibit heterocyst differentiation in neighboring vegetative cells, thus contributing to pattern formation and spacing of heterocysts along the filament. While overexpression of PatS suppresses heterocyst differentiation in Nostoc sp. PCC 7120, overexpression of HetL produces a multiple contiguous heterocyst phenotype with loss of the wild type heterocyst pattern, and strains containing extra copies of hetL allow heterocyst formation even in cells overexpressing PatS. Thus, HetL appears to interfere with heterocyst differentiation inhibition by PatS, however, the mechanism for HetL function remains unknown. As a first step towards exploring the mechanism for its biochemical function, the crystal structure of HetL has been solved at 2.0 angstrom resolution using sulfur anomalous scattering. (C) 2008 Published by Elsevier Inc.