Affiliations 

  • 1 Centre for Chemical Biology, Universiti Sains Malaysia, 10 Persiaran Bukit Jambul, 11900 Bayan Lepas, Penang, Malaysia
  • 2 Department of Microbiology, University of Hawaii, 2538 McCarthy Mall, Honolulu, HI 96822, United States
  • 3 School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
  • 4 1] Department of Microbiology, University of Hawaii, 2538 McCarthy Mall, Honolulu, HI 96822, United States [2] Advanced Studies in Genomics, Proteomics and Bioinformatics, University of Hawaii, 2565 McCarthy Mall, Honolulu, HI 96822, United States
Sci Rep, 2015;5:11407.
PMID: 26094577 DOI: 10.1038/srep11407

Abstract

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.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.