title: Detection and characterisation of mutations responsible for allele-specific protein thermostabilities at the Mn-superoxide dismutase gene in the deep-sea hydrothermal vent polychaete Alvinella pompejana.
abstract: Alvinella pompejana (Polychaeta, Alvinellidae) is one of the most thermotolerant marine eukaryotes known to date. It inhabits chimney walls of deep-sea hydrothermal vents along the East Pacific Rise (EPR) and is exposed to various challenging conditions (e.g. high temperature, hypoxia and the presence of sulphides, heavy metals and radiations), which increase the production of dangerous reactive oxygen species (ROS). Two different allelic forms of a manganese-superoxide dismutase involved in ROS detoxification, ApMnSOD1 and ApMnSOD2, and differing only by two substitutions (M110L and A138G) were identified in an A. pompejana cDNA library. RFLP screening of 60 individuals from different localities along the EPR showed that ApMnSOD2 was rare (2 %) and only found in the heterozygous state. Dynamic light scattering measurements and residual enzymatic activity experiments showed that the most frequent form (ApMnSOD1) was the most resistant to temperature. Their half-lives were similarly long at 65 °C (>110 min) but exhibited a twofold difference at 80 °C (20.8 vs 9.8 min). Those properties are likely to be explained by the occurrence of an additional sulphur-containing hydrogen bond involving the M110 residue and the effect of the A138 residue on the backbone entropy. Our results confirm the thermophily of A. pompejana and suggest that this locus is a good model to study how the extreme thermal heterogeneity of the vent conditions may help to maintain old rare variants in those populations.
authors.affiliation: UPMC Université Pierre-et-Marie Curie, UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, 29680, Roscoff, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Bruneaux
authors.forename: Jean
authors.initials: J
authors.lastname: Mary
authors.forename: Marie
authors.initials: M
authors.lastname: Verheye
authors.forename: Odile
authors.initials: O
authors.lastname: Lecompte
authors.forename: Olivier
authors.initials: O
authors.lastname: Poch
authors.forename: Didier
authors.initials: D
authors.lastname: Jollivet
authors.forename: Arnaud
authors.initials: A
authors.lastname: Tanguy
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D004926:Escherichia coli / Q000235:genetics; D015723:Gene Library; D006207:Half-Life; D006358:Hot Temperature; D060086:Hydrothermal Vents; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009792:Oceans and Seas; D011077:Polychaeta / Q000201:enzymology / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2
chemical_list: D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2