文章基本信息

标题：Open and Lys–His Hexacoordinated Closed Structures of a Globin with Swapped Proximal and Distal Sites
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作者：Aik-Hong Teh ; Jennifer A. Saito ; Nazalan Najimudin 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
期号：1
DOI：10.1038/srep11407
语种：English
出版社：Springer Nature
摘要：Globins are haem-binding proteins with a conserved fold made up of α-helices and can possess diverse properties. A putative globin-coupled sensor from Methylacidiphilum infernorum, HGbRL, contains an N-terminal globin domain whose open and closed structures reveal an untypical dimeric architecture. Helices E and F fuse into an elongated helix, resulting in a novel site-swapped globin fold made up of helices A-E, hence the distal site, from one subunit and helices F-H, the proximal site, from another. The open structure possesses a large cavity binding an imidazole molecule, while the closed structure forms a unique Lys-His hexacoordinated species, with the first turn of helix E unravelling to allow Lys52(E10) to bind to the haem. Ligand binding induces reorganization of loop CE, which is stabilized in the closed form, and helix E, triggering a large conformational movement in the open form. These provide a mechanical insight into how a signal may be relayed between the globin domain and the C-terminal domain of HGbRL, a Roadblock/LC7 domain. Comparison with HGbI, a closely related globin, further underlines the high degree of structural versatility that the globin fold is capable of, enabling it to perform a diversity of functions.