4-hydroxybenzoyl-CoA reductase (dehydroxylating) from the denitrifying bacterium Thauera aromatica -: Prosthetic groups, electron donor, and genes of a member of the molybdenum-flavin-iron-sulfur proteins
4-hydroxybenzoyl-CoA reductase (dehydroxylating) from the denitrifying bacterium Thauera aromatica -: Prosthetic groups, electron donor, and genes of a member of the molybdenum-flavin-iron-sulfur proteins
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DOI：
10.1046/j.1432-1327.1998.2510916.x
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发表时间：
1998-02-01
期刊：
影响因子：
--
通讯作者：
Fuchs, G
中科院分区：
文献类型：
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作者：
Breese, K;Fuchs, G
4-羟基苯甲酰基-CoA还原酶催化酚类化合物厌氧代谢中的重要反应，即芳香族羟基的还原去除。对酶的辅基和天然电子供体进行了研究，并对基因进行了克隆和测序。该酶是一种由α（2）β（2）γ（2）亚基组成的黄素-铁-硫蛋白，含有约1.3个黄素核苷酸（可能是FAD）、1.9个钼、15个铁和12.5个酸不稳定硫。序列分析表明，天然酶含有两个[4Fe-4S]和四个[2Fe-2S]簇。具有两个[4Fe-4S]簇的9.8-kDa铁氧还蛋白作为天然电子供体。编码三个亚基的基因hcrABC与黄嘌呤氧化酶家族的其他黄素-铁-硫蛋白具有高度相似性，特别是与沼泽红球藻中的三个推定的4-羟基苯甲酰基-CoA还原酶基因具有高度相似性。此外，E.杆菌一个主要的区别是β亚基（HcrB，35 kDa）中存在一个额外的结构域，可能携带一个额外的铁硫簇，82 kDa的α亚基（HcrA）含有一个Mo-辅因子结合位点。17-kDa的γ亚基（HcrC）含有两个[2Fe-2S]簇，在hcrCAB区的上游有一个编码马尔R家族调节蛋白的ORF，在hcrCAB区的下游有一个编码疏水性通透酶的ORF。
4-Hydroxybenzoyl-CoA reductase catalyzes an important reaction in the anaerobic metabolism of phenolic compounds, i.e, the reductive removal of an aromatic hydroxyl group. The prosthetic groups and the natural electron donor of the enzyme were investigated and the genes were cloned and sequenced. The enzyme is a molybdenum-flavin-iron-sulfur protein of subunit composition of alpha(2) beta(2) gamma(2).It contains approximately 1.3 flavin nucleotide, probably FAD, 1.9 Mo, 15 Fe, and 12.5 acid-labile sulfur. Sequence interpretation suggests that the native enzyme contains two [4Fe-4S] and four [2Fe-2S] clusters. A 9.8-kDa ferredoxin with two [4Fe-4S] clusters functions as the natural electron donor. The genes coding for the three subunits, hcrABC, show high similarities to other molybdenum-flavin-iron-sulfur proteins of the xanthine oxidase family, notably to the three putative 4-hydroxybenzoyl-CoA reductase genes in Rhodopseudomonas palustris. In addition, there are close similarities to three open reading frames (orf) in E. coli. A major difference is the presence of an additional domain in the beta-subunit (HcrB, 35 kDa) probably carrying an additional iron-sulfur cluster, The 82-kDa alpha-subunit (HcrA) contains a Mo-cofactor-binding site. The 17-kDa gamma-subunit (HcrC) harbors two [2Fe-2S] clusters, Upstream of the hcrCAB region, an ORF was found coding for a regulatory protein of the MarR family, Downstream of the hcrCAB region lies an ORF presumably coding for a hydrophobic permease.