Structural highlights
Publication Abstract from PubMedGlobins are haem-binding proteins with a conserved fold made up of alpha-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. Open and Lys-His Hexacoordinated Closed Structures of a Globin with Swapped Proximal and Distal Sites.,Teh AH, Saito JA, Najimudin N, Alam M Sci Rep. 2015 Jun 22;5:11407. doi: 10.1038/srep11407. PMID:26094577[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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