The alternative route to heme in the methanogenic archaeon Methanosarcina barkeri.
The alternative route to heme in the methanogenic archaeon Methanosarcina barkeri.
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DOI：
10.1155/2014/327637
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Layer G
中科院分区：
文献类型：
--
作者：
Kühner M;Haufschildt K;Neumann A;Storbeck S;Streif J;Layer G
在生物体中，血红素由共同的前体尿卟啉原III通过两种基本上不同的途径之一形成。与采用所谓的“经典”血红素生物合成途径的真核生物和大多数细菌相反，古细菌使用替代途径。在该途径中，血红素由尿卟啉原III通过中间体前卟啉-2、西罗氢二氢卟啉、西罗血红素、12，18-二脱羧基西罗血红素和铁粪卟啉III形成。在这项研究中，血红素生物合成蛋白AhbAB，AhbC和AhbD从甲烷八叠球菌巴克氏功能的特点。使用体内酶活性测定，显示AhbA和AhbB（Mbar_A1459和Mbar_A1460）一起催化西罗血红素转化为12，18-二脱羧基西罗血红素。这两种蛋白质形成异二聚体复合物，其可能受到通路终产物血红素的反馈调节。此外，AhbC（Mbar_A1793）显示在体内催化铁-粪卟啉III的形成。最后，在大肠杆菌中表达了重组AhbD（Mbar_A1458）。表明该蛋白很可能含有两个[4Fe-4S]簇。使用体外酶活性测定，结果表明，AhbD催化铁粪卟啉III转化为血红素。
In living organisms heme is formed from the common precursor uroporphyrinogen III by either one of two substantially different pathways. In contrast to eukaryotes and most bacteria which employ the so-called “classical” heme biosynthesis pathway, the archaea use an alternative route. In this pathway, heme is formed from uroporphyrinogen III via the intermediates precorrin-2, sirohydrochlorin, siroheme, 12,18-didecarboxysiroheme, and iron-coproporphyrin III. In this study the heme biosynthesis proteins AhbAB, AhbC, and AhbD from Methanosarcina barkeri were functionally characterized. Using an in vivo enzyme activity assay it was shown that AhbA and AhbB (Mbar_A1459 and Mbar_A1460) together catalyze the conversion of siroheme into 12,18-didecarboxysiroheme. The two proteins form a heterodimeric complex which might be subject to feedback regulation by the pathway end-product heme. Further, AhbC (Mbar_A1793) was shown to catalyze the formation of iron-coproporphyrin III in vivo. Finally, recombinant AhbD (Mbar_A1458) was produced in E. coli and purified indicating that this protein most likely contains two [4Fe-4S] clusters. Using an in vitro enzyme activity assay it was demonstrated that AhbD catalyzes the conversion of iron-coproporphyrin III into heme.
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影响因子：
14.8
作者：
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通讯作者：
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