title: Ancestral hemoglobins in Archaea.
abstract: Hemoglobins are ubiquitous in Eukarya and Bacteria but, until now, have not been found in Archaea. A phylogenetic analysis of the recently revealed microbial family of globin-coupled heme-based sensors suggests that these sensors descended from an ancient globin-only progenitor, or a protoglobin (Pgb). Here, we report the discovery and characterization of two Pgbs from the Archaea: ApPgb from the obligately aerobic hyperthermophile Aeropyrum pernix, and MaPgb from the strictly anaerobic methanogen Methanosarcina acetivorans. Both ApPgb and MaPgb bind molecular oxygen, nitric oxide, and carbon monoxide by means of a heme moiety that is coordinated to the protein through the F8 histidine (histidine 120). We postulate that these archaeal globins are the ancestors of contemporary hemoglobins.
authors.affiliation: Department of Microbiology, Snyder Hall 207, 2538 The Mall, University of Hawaii, Honolulu, HI 96822, USA.
authors.forename: Tracey Allen K
authors.initials: TA
authors.lastname: Freitas
authors.forename: Shaobin
authors.initials: S
authors.lastname: Hou
authors.forename: Elhadji M
authors.initials: EM
authors.lastname: Dioum
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Saito
authors.forename: James
authors.initials: J
authors.lastname: Newhouse
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Gonzalez
authors.forename: Marie-Alda
authors.initials: MA
authors.lastname: Gilles-Gonzalez
authors.forename: Maqsudul
authors.initials: M
authors.lastname: Alam
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000737:chemistry*; D001483:Base Sequence; D002248:Carbon Monoxide / Q000378:metabolism; D017931:DNA Primers; D006454:Hemoglobins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013056:Spectrophotometry, Ultraviolet
chemical_list: D017931:DNA Primers; D006454:Hemoglobins; D009569:Nitric Oxide; D002248:Carbon Monoxide; D010100:Oxygen