title: Structure and evolution of the actin gene family in Arabidopsis thaliana.
abstract: Higher plants contain families of actin-encoding genes that are divergent and differentially expressed. Progress in understanding the functions and evolution of plant actins has been hindered by the large size of the actin gene families. In this study, we characterized the structure and evolution of the actin gene family in Arabidopsis thaliana. DNA blot analyses with gene-specific probes suggested that all 10 of the Arabidopsis actin gene family members have been isolated and established that Arabidopsis has a much simpler actin gene family than other plants that have been examined. Phylogenetic analyses suggested that the Arabidopsis gene family contains at least two ancient classes of genes that diverged early in land plant evolution and may have separated vegetative from reproductive actins. Subsequent divergence produced a total of six distinct subclasses of actin, and five showed a distinct pattern of tissue specific expression. The concordance of expression patterns with the phylogenetic structure is discussed. These subclasses appear to be evolving independently, as no evidence of gene conversion was found. The Arabidopsis actin proteins have an unusually large number of nonconservative amino acid substitutions, which mapped to the surface of the actin molecule, and should effect protein-protein interactions.
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill 27599, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: McDowell
authors.forename: S
authors.initials: S
authors.lastname: Huang
authors.forename: E C
authors.initials: EC
authors.lastname: McKinney
authors.forename: Y Q
authors.initials: YQ
authors.lastname: An
authors.forename: R B
authors.initials: RB
authors.lastname: Meagher
mesh_terms: D000199:Actins / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D017931:DNA Primers; D014644:Genetic Variation; D018745:Genome, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*
chemical_list: D000199:Actins; D017931:DNA Primers; D010940:Plant Proteins