title: Globin's structure and function in vesicomyid bivalves from the Gulf of Guinea cold seeps as an adaptation to life in reduced sediments.
abstract: Vesicomyid bivalves form dense clam beds in both deep-sea cold seeps and hydrothermal vents. The species diversity within this family raises questions about niche separation and specific adaptations. To compare their abilities to withstand hypoxia, we have studied the structure and function of erythrocyte hemoglobin (Hb) and foot myoglobin (Mb) from two vesicomyid species, Christineconcha regab and Laubiericoncha chuni, collected from the Regab pockmark in the Gulf of Guinea at a depth of 3,000 m. Laubiericoncha chuni possesses three monomeric globins, G1 (15,361 Da), G2 (15,668 Da), and G3 (15,682 Da) in circulating erythrocytes (Hb), and also three globins, G1, G3, and G4 (14,786 Da) in foot muscle (Mb). Therefore, globins G2 and G4 appear to be specific for erythrocytes and muscle, respectively, but globins G1 and G3 are common. In contrast, C. regab lacks erythrocyte Hb completely and possesses only globin monomers G1' (14,941 Da), G2' (15,169 Da), and G3' (15,683 Da) in foot muscle. Thus, these two vesicomyid species, C. regab and L. chuni, show a remarkable diversity in globin expression when examined by electrospray ionization mass spectrometry. Oxygen-binding affinities reveal extremely high oxygen affinities (P50 < 1 Torr, from 5° to 15°C at pH 7.5), in particular L. chuni globins, which might be an advantage allowing L. chuni to dig deeply for sulfides and remain buried for long periods in reduced sediments.
authors.affiliation: IFREMER, Laboratoire Environnement Profond, Unité de Recherche Etude des Ecosystèmes Profonds, F-29280 Plouzané, France; 2Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche (UMR) 7144, Équipe Adaptation et Biologie des Invertébrés en Conditions Extrêmes, Station Biologique, F-29680 Roscoff, France; 3Centre National de la Recherche Scientifique (CNRS), UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique, F-29680 Roscoff, France; 4Laboratoire de Spectrométrie de Masse des Interactions et des Systèmes, UMR 7140, CNRS-Université Louis Pasteur Chimie de la Matière Complexe, F-67008 Strasbourg, France.
authors.forename: C
authors.initials: C
authors.lastname: Decker
authors.forename: N
authors.initials: N
authors.lastname: Zorn
authors.forename: N
authors.initials: N
authors.lastname: Potier
authors.forename: E
authors.initials: E
authors.lastname: Leize-Wagner
authors.forename: F H
authors.initials: FH
authors.lastname: Lallier
authors.forename: K
authors.initials: K
authors.lastname: Olu
authors.forename: A C
authors.initials: AC
authors.lastname: Andersen
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001267:Atlantic Ocean; D049872:Bivalvia / Q000378:metabolism*; D017753:Ecosystem; D004912:Erythrocytes / Q000737:chemistry / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D021122:Protein Subunits / Q000737:chemistry; D015657:Respiratory Transport; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; D021122:Protein Subunits