title: Molecular phylogeny and evolution of the plant-specific seven-transmembrane MLO family.
abstract: Homologues of barley Mlo encode the only family of seven-transmembrane (TM) proteins in plants. Their topology, subcellular localization, and sequence diversification are reminiscent of those of G-protein coupled receptors (GPCRs) from animals and fungi. We present a computational analysis of MLO family members based on 31 full-size and 3 partial sequences, which originate from several monocot species, the dicot Arabidopsis thaliana, and the moss Ceratodon purpureus. This enabled us to date the origin of the Mlo gene family back at least to the early stages of land plant evolution. The genomic organization of the corresponding genes supports a monophyletic origin of the Mlo gene family. Phylogenetic analysis revealed five clades, of which three contain both monocot and dicot members, while two indicate class-specific diversification. Analysis of the ratio of nonsynonymous-to-synonymous changes in coding sequences provided evidence for functional constraint on the evolution of the DNA sequences and purifying selection, which appears to be reduced in the first extracellular loop of 12 closely related orthologues. The 31 full-size sequences were examined for potential domain-specific intramolecular coevolution. This revealed evidence for concerted evolution of all three cytoplasmic domains with each other and the C-terminal cytoplasmic tail, suggesting interplay of all intracellular domains for MLO function.
authors.affiliation: Sainsbury Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, UK.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Devoto
authors.forename: H Andreas
authors.initials: HA
authors.lastname: Hartmann
authors.forename: Pietro
authors.initials: P
authors.lastname: Piffanelli
authors.forename: Candace
authors.initials: C
authors.lastname: Elliott
authors.forename: Carl
authors.initials: C
authors.lastname: Simmons
authors.forename: Graziana
authors.initials: G
authors.lastname: Taramino
authors.forename: Chern-Sing
authors.initials: CS
authors.lastname: Goh
authors.forename: Fred E
authors.initials: FE
authors.lastname: Cohen
authors.forename: Brent C
authors.initials: BC
authors.lastname: Emerson
authors.forename: Paul
authors.initials: P
authors.lastname: Schulze-Lefert
authors.forename: Ralph
authors.initials: R
authors.lastname: Panstruga
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D016415:Sequence Alignment; D003313:Zea mays / Q000235:genetics*
chemical_list: D010940:Plant Proteins