Cosper N J, Stålhandske C M, Iwasaki H, Oshima T, Scott R A, Iwasaki T
Center for Metalloenzyme Studies and Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA.
J Biol Chem. 1999 Aug 13;274(33):23160-8. doi: 10.1074/jbc.274.33.23160.
The zfx gene encoding a zinc-containing ferredoxin from Thermoplasma acidophilum strain HO-62 was cloned and sequenced. It is located upstream of two genes encoding an archaeal homolog of nascent polypeptide-associated complex alpha subunit and a tRNA nucleotidyltransferase. This gene organization is not conserved in several euryarchaeoteal genomes. The multiple sequence alignments of the zfx gene product suggest significant sequence similarity of the ferredoxin core fold to that of a low potential 8Fe-containing dicluster ferredoxin without a zinc center. The tightly bound zinc site of zinc-containing ferredoxins from two phylogenetically distantly related Archaea, T. acidophilum HO-62 and Sulfolobus sp. strain 7, was further investigated by x-ray absorption spectroscopy. The zinc K-edge x-ray absorption spectra of both archaeal ferredoxins are strikingly similar, demonstrating that the same zinc site is found in T. acidophilum ferredoxin as in Sulfolobus sp. ferredoxin, which suggests the structural conservation of isolated zinc binding sites among archaeal zinc-containing ferredoxins. The sequence and spectroscopic data provide the common structural features of the archaeal zinc-containing ferredoxin family.
对嗜酸嗜热栖热菌HO-62菌株中编码含锌铁氧化还原蛋白的zfx基因进行了克隆和测序。它位于编码新生多肽相关复合物α亚基的古菌同源物和一种tRNA核苷酸转移酶的两个基因的上游。这种基因组织在几个广古菌基因组中并不保守。zfx基因产物的多序列比对表明，铁氧化还原蛋白核心折叠与不含锌中心的低电位含8个铁的双簇铁氧化还原蛋白具有显著的序列相似性。通过X射线吸收光谱进一步研究了来自两个系统发育关系较远的古菌——嗜酸嗜热栖热菌HO-62和硫磺菌属菌株7的含锌铁氧化还原蛋白的紧密结合锌位点。两种古菌铁氧化还原蛋白的锌K边X射线吸收光谱惊人地相似，表明嗜酸嗜热栖热菌铁氧化还原蛋白中的锌位点与硫磺菌属铁氧化还原蛋白中的锌位点相同，这表明在古菌含锌铁氧化还原蛋白中分离的锌结合位点具有结构保守性。序列和光谱数据提供了古菌含锌铁氧化还原蛋白家族的共同结构特征。
