Wang Zhongmin, Li Chester, Ellenburg Melanie, Soistman Elizabeth, Ruble John, Wright Brenda, Ho Joseph X, Carter Daniel C
New Century Pharmaceuticals Inc., 895 Martin Road, Huntsville, Alabama 35824, USA.
Acta Crystallogr D Biol Crystallogr. 2006 Jul;62(Pt 7):800-6. doi: 10.1107/S0907444906018294. Epub 2006 Jun 20.
Ferritin is the major iron-storage protein present in all cells. It generally contains 24 subunits, with different ratios of heavy chain (H) to light chain (L), in the shape of a hollow sphere hosting up to 4500 ferric Fe atoms inside. H-rich ferritins catalyse the oxidation of iron(II), while L-rich ferritins promote the nucleation and storage of iron(III). Several X-ray structures have been determined, including those of L-chain ferritins from horse spleen (HoSF), recombinant L-chain ferritins from horse (HoLF), mouse (MoLF) and bullfrog (BfLF) as well as recombinant human H-chain ferritin (HuHF). Here, structures have been determined of two crystal forms of recombinant human L-chain ferritin (HuLF) obtained from native and perdeuterated proteins. The structures show a cluster of acidic residues at the ferrihydrite nucleation site and at the iron channel along the threefold axis. An ordered Cd2+ structure is observed within the iron channel, offering further insight into the route and mechanism of iron transport into the capsid. The loop between helices D and E, which is disordered in many other L-chain structures, is clearly visible in these two structures. The crystals generated from perdeuterated HuLF will be used for neutron diffraction studies.
铁蛋白是所有细胞中存在的主要铁储存蛋白。它通常包含24个亚基，重链（H）与轻链（L）的比例不同，呈空心球体形状，内部可容纳多达4500个三价铁原子。富含H的铁蛋白催化亚铁的氧化，而富含L的铁蛋白促进三价铁的成核和储存。已经确定了几种X射线结构，包括来自马脾的L链铁蛋白（HoSF）、来自马（HoLF）、小鼠（MoLF）和牛蛙（BfLF）的重组L链铁蛋白以及重组人H链铁蛋白（HuHF）。在此，已确定了从天然和全氘代蛋白质获得的重组人L链铁蛋白（HuLF）的两种晶体形式的结构。这些结构显示在三水铁矿成核位点和沿三重轴的铁通道处有一簇酸性残基。在铁通道内观察到有序的Cd2+结构，这为铁进入衣壳的途径和机制提供了进一步的见解。在许多其他L链结构中无序的螺旋D和E之间的环在这两种结构中清晰可见。由全氘代HuLF生成的晶体将用于中子衍射研究。
