title: Evolution under pressure and the adaptation of visual pigment compressibility in deep-sea environments.
abstract: Understanding the link between how proteins function in animals that live in extreme environments and selection on specific properties of amino acids has proved extremely challenging. Here we present the discovery of how the compressibility of opsin proteins in two evolutionarily distinct animal groups, teleosts and cephalopods, appears to be adapted to the high-pressure environment of the deep-sea. We report how in both groups, opsins in deeper living species are calculated to be less compressible. This is largely due to a common set of amino acid sites (bovRH# 159, 196, 213, 275) undergoing positive destabilizing selection in six of the twelve amino acid physiochemical properties that determine protein compressibility. This suggests a common evolutionary mechanism to reduce the adiabatic compressibility of opsin proteins. Intriguingly, the sites under selection are on the proteins' outer faces at locations known to be involved in opsin-opsin dimer interactions.
authors.affiliation: Department of Biology, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Porter
authors.affiliation: School of Biological Sciences, University of Bristol, Tyndall Avenue, Bristol BS8 1TQ, UK. Electronic address: nicholas.roberts@bristol.ac.uk.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Roberts
authors.affiliation: School of Animal Biology and the Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Julian C
authors.initials: JC
authors.lastname: Partridge
mesh_terms: D000064:Acclimatization; D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D004777:Environment; D059647:Gene-Environment Interaction; D055355:Opsins / Q000737:chemistry / Q000235:genetics; D010802:Phylogeny
chemical_list: D055355:Opsins
keywords: Cephalopod; Compressibility; Deep-sea; Evolution; Opsin; Teleost