title: Microbial rhodopsins: functional versatility and genetic mobility.
abstract: The type 1 (microbial) rhodopsins are a diverse group of photochemically reactive proteins that span the three domains of life. Their broad phylogenetic distribution has motivated conjecture that rhodopsin-like functionality was present in the last common ancestor of all life. Here, we discuss the evolution of the type 1 microbial rhodopsins and document five cases of lateral gene transfer (LGT) between domains. We suggest that, thanks to the functional versatility of these retinylidene proteins and the relative ease with which they can complement the existing energy-generating or photosensory repertoires of many organisms, LGT is in fact the principal force that determines their broad but patchy distribution.
authors.affiliation: Department of Biochemistry and Molecular Biology, Dalhousie University, 5850 College St, Halifax, Nova Scotia B3H 1X5, Canada. aksharma@dal.ca
authors.forename: Adrian K
authors.initials: AK
authors.lastname: Sharma
authors.forename: John L
authors.initials: JL
authors.lastname: Spudich
authors.forename: W Ford
authors.initials: WF
authors.lastname: Doolittle
mesh_terms: D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D010802:Phylogeny; D025604:Rhodopsins, Microbial / Q000235:genetics* / Q000502:physiology
chemical_list: D025604:Rhodopsins, Microbial