Crystal structure of PhnH:: an essential component of carbon-phosphorus lyase in Escherichia coli
Crystal structure of PhnH:: an essential component of carbon-phosphorus lyase in Escherichia coli
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DOI：
10.1128/jb.01274-07
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发表时间：
2008-02-01
影响因子：
3.2
通讯作者：
Jia, Zongchao
中科院分区：
文献类型：
--
作者：
Adams, Melanie A.;Luo, Yan;Jia, Zongchao
有机磷酸盐是磷的还原形式，其特征是存在稳定的碳-磷(C-P)键，该键可抵抗化学水解、热分解和光解。随着有毒的磷酸盐在许多生态系统中积累，C-P键的化学惰性引起了环境问题的关注。碳-磷裂解酶(CP裂解酶)是革兰氏阴性菌中由PHN操纵子编码的一种多酶途径。在大肠杆菌中，14个顺反子组成操纵子(PhnCDEFGHIJKLM NOP)，共同允许磷酸盐的内化和降解。这里我们报道了PhnH组分在1.77埃分辨率下的X射线晶体结构。该蛋白显示了一个新的折叠，尽管与依赖于吡哆醛5‘-磷酸转移酶家族的蛋白质有明显的局部相似性。PhnH在溶液和晶体结构中形成二聚体，其界面与产生潜在的配体结合口袋有关。我们的研究进一步表明，PhnH可能能够通过与严格保守的残基相互作用而结合带负电荷的环状化合物。最后，我们证明了在CP裂解酶途径中，PhnH是C-P键断裂所必需的。
Organophosphonates are reduced forms of phosphorous that are characterized by the presence of a stable carbon-phosphorus (C-P) bond, which resists chemical hydrolysis, thermal decomposition, and photolysis. The chemically inert nature of the C-P bond has raised environmental concerns as toxic phosphonates accumulate in a number of ecosystems. Carbon-phosphorous lyase (CP lyase) is a multienzyme pathway encoded by the phn operon in gram-negative bacteria. In Escherichia coli 14 cistrons comprise the operon (phnCDEFGHIJKLM NOP) and collectively allow the internalization and degradation of phosphonates. Here we report the X-ray crystal structure of the PhnH component at 1.77 angstrom resolution. The protein exhibits a novel fold, although local similarities with the pyridoxal 5'-phosphate-dependent transferase family of proteins are apparent. PhnH forms a dimer in solution and in the crystal structure, the interface of which is implicated in creating a potential ligand binding pocket. Our studies further suggest that PhnH may be capable of binding negatively charged cyclic compounds through interaction with strictly conserved residues. Finally, we show that PhnH is essential for C-P bond cleavage in the CP lyase pathway.