来自一种极端嗜热嗜酸细菌的截短血红蛋白的晶体结构。

Crystal structure of truncated haemoglobin from an extremely thermophilic and acidophilic bacterium.

作者信息

Jamil Farrukh, Teh Aik-Hong, Schadich Ermin, Saito Jennifer A, Najimudin Nazalan, Alam Maqsudul

机构信息

Centre for Chemical Biology, Universiti Sains Malaysia, 10 Persiaran Bukit Jambul, 11900 Bayan Lepas, Penang, Malaysia; School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand; Advanced Studies in Genomics, Proteomics and Bioinformatics, University of Hawaii, 2565 McCarthy Mall, Honolulu, HI 96822, USA; School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia; and Department of Microbiology, University of Hawaii, 2538 McCarthy Mall, Honolulu, HI 96822, USA

出版信息

J Biochem. 2014 Aug;156(2):97-106. doi: 10.1093/jb/mvu023. Epub 2014 Apr 14.

DOI:10.1093/jb/mvu023

PMID:24733432

Abstract

A truncated haemoglobin (tHb) has been identified in an acidophilic and thermophilic methanotroph Methylacidiphilium infernorum. Hell's Gate Globin IV (HGbIV) and its related tHbs differ from all other bacterial tHbs due to their distinctively large sequence and polar distal haem pocket residues. Here we report the crystal structure of HGbIV determined at 1.96 Å resolution. The HGbIV structure has the distinctive 2/2 α-helical structure with extensions at both termini. It has a large distal site cavity in the haem pocket surrounded by four polar residues: His70(B9), His71(B10), Ser97(E11) and Trp137(G8). This cavity can bind bulky ligands such as a phosphate ion. Conformational shifts of His71(B10), Leu90(E4) and Leu93(E7) can also provide more space to accommodate larger ligands than the phosphate ion. The entrance/exit of such bulky ligands might be facilitated by positional flexibility in the CD1 loop, E helix and haem-propionate A. Therefore, the large cavity in HGbIV with polar His70(B9) and His71(B10), in contrast to the distal sites of other bacterial tHbs surrounded by non-polar residues, suggests its distinct physiological functions.

摘要

在嗜酸性嗜热甲烷氧化菌“地狱之门嗜甲基菌”（Methylacidiphilium infernorum）中发现了一种截短血红蛋白（tHb）。“地狱之门球蛋白IV”（HGbIV）及其相关的tHb与所有其他细菌tHb不同，因为它们具有明显较大的序列以及极性的远侧血红素口袋残基。在此，我们报道了分辨率为1.96 Å时测定的HGbIV晶体结构。HGbIV结构具有独特的2/2 α-螺旋结构，两端都有延伸。它在血红素口袋中有一个大的远侧位点腔，被四个极性残基包围：His70（B9）、His71（B10）、Ser97（E11）和Trp137（G8）。这个腔可以结合诸如磷酸根离子等体积较大的配体。His71（B10）、Leu90（E4）和Leu93（E7）的构象变化也可以提供更多空间来容纳比磷酸根离子更大的配体。CD1环、E螺旋和血红素丙酸酯A中的位置灵活性可能有助于这种体积较大的配体进出。因此，与其他被非极性残基包围的细菌tHb远侧位点相比，HGbIV中带有极性His70（B9）和His71（B10）的大腔表明其具有独特的生理功能。