title: Ancient gene duplication and differential gene flow in plastid lineages: the GroEL/Cpn60 example.
abstract: Cryptomonads, small biflagellate algae, contain four different genomes. In addition to the nucleus, mitochondrion, and chloroplast is a fourth DNA-containing organelle the nucleomorph. Nucleomorphs result from the successive reduction of the nucleus of an engulfed phototrophic eukaryotic endosymbiont by a secondary eukaryotic host cell. By sequencing the chloroplast genome and the nucleomorph chromosomes, we identified a groEL homologue in the genome of the chloroplast and a related cpn60 in one of the nucleomorph chromosomes. The nucleomorph-encoded Cpn60 and the chloroplast-encoded GroEL correspond in each case to one of the two divergent GroEL homologues in the cyanobacterium Synechocystis sp. PCC6803. The coexistence of divergent groEL/cpn60 genes in different genomes in one cell offers insights into gene transfer from evolving chloroplasts to cell nuclei and convergent gene evolution in chlorophyll a/b versus chlorophyll a/c/phycobilin eukaryotic lineages.
authors.affiliation: Cell Biology and Applied Botany, Philipps-Universität Marburg, Karl-von-Frisch-Strasse, D-35032 Marburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wastl
authors.forename: M
authors.initials: M
authors.lastname: Fraunholz
authors.forename: S
authors.initials: S
authors.lastname: Zauner
authors.forename: S
authors.initials: S
authors.lastname: Douglas
authors.forename: U G
authors.initials: UG
authors.lastname: Maier
mesh_terms: D000595:Amino Acid Sequence; D018834:Chaperonin 60 / Q000235:genetics*; D002736:Chloroplasts / Q000235:genetics; D056890:Eukaryota / Q000145:classification / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D018087:Plastids / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D018834:Chaperonin 60; D010940:Plant Proteins