Structural Studies of Hydroxylamine Oxidoreductase Reveal a Unique Heme Cofactor and a Previously Unidentified Interaction Partner

被引：62

作者：

Cedervall, Peder ^{[1
]}

Hooper, Alan B. ^{[1
]}

Wilmot, Carrie M. ^{[1
]}

机构：

[1] Univ Minnesota, Dept Biochem Mol Biol & Biophys, Minneapolis, MN 55455 USA

来源：

BIOCHEMISTRY | 2013年 / 52卷 / 36期

基金：

美国国家卫生研究院;

关键词：

AMMONIA-OXIDIZING BACTERIA; NITROSOMONAS-EUROPAEA; CYTOCHROME P460; CRYSTAL-STRUCTURE; CROSS-LINK; PROTEIN; MODEL; CONSERVATION; PURIFICATION; REDUCTION;

D O I：

10.1021/bi400960w

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Hydroxylamine oxidoreductase (HAO) is a 24-heme homotrimeric enzyme that catalyzes the conversion of hydroxylamine to nitrite in nitrifying bacteria: a key reaction in the nitrogen cycle. One heme in each HAO monomer is a highly unusual heme P460 that is the site of catalysis. This was proposed to be a c-type heme that contained an addition porphyrin-tyrosine cross-link. Here, we report the crystal structure of HAO from Nitrosomonas europaea to 2.1 angstrom resolution that defines a different model compatible with the crystallographic and biochemical data. The structure reveals that heme P460 contains two covalent cross-links between the porphyrin and a Tyr residue. In addition, the enzyme was purified from source, and an unknown physiological HAO binding partner was present within the crystal (annotated in the genome as hypothetical protein NE1300). NE1300 may play a structural role in the ternary complex with cytochrome c(554), the physiological electron acceptor of HAO.

引用

页码：6211 / 6218

页数：8

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