Fushinobu Shinya, Shoun Hirofumi, Wakagi Takayoshi
Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Biochemistry. 2003 Oct 14;42(40):11707-15. doi: 10.1021/bi034220b.
Sulerythrin is the first rubrerythrin-like protein to be isolated from an aerobic organism, Sulfolobus tokodaii strain 7, and it lacks a C-terminal rubredoxin-like FeS(4) domain. The protein purified from Sulfolobus cells was crystallized, and the crystal structure was determined at 1.7 A resolution. The dimer of sulerythrin exhibited "domain-swapping" at the loop connecting alphaB and alphaC, hybrid four-helix bundles consisting of alphaA/B and alphaC/D being formed. The structure and atomic identity of the binuclear metal center were determined by means of anomalous scattering analysis. The site contained 1.0 mol of hexacoordinate Fe, 0.80-0.87 mol of tetracoordinate Zn, and 0.73-0.88 mol of putative O(2) per monomer. The metal ions were found at exchanged positions compared to those in the Fe/Zn-containing rubrerythrin from Desulfovibrio vulgaris. The results demonstrate that the binuclear metal center of rubrerythrin-like proteins is plastic in its ability to bind metal ions.
嗜热栖热放线菌红素是从需氧生物嗜热栖热放线菌7株中分离出的首个类红素蛋白，它缺乏C末端类红氧还蛋白的FeS(4)结构域。从嗜热栖热放线菌细胞中纯化得到的该蛋白被结晶，其晶体结构在1.7埃分辨率下得以确定。嗜热栖热放线菌红素二聚体在连接αB和αC的环处呈现“结构域交换”，形成了由αA/B和αC/D组成的杂合四螺旋束。通过反常散射分析确定了双核金属中心的结构和原子特性。该位点每个单体含有1.0摩尔的六配位铁、0.80 - 0.87摩尔的四配位锌以及0.73 - 0.88摩尔的假定的O(2)。与来自普通脱硫弧菌的含Fe/Zn红素相比，发现金属离子处于交换后的位置。结果表明，类红素蛋白的双核金属中心在结合金属离子的能力方面具有可塑性。
