title: Differential gene transfers and gene duplications in primary and secondary endosymbioses.
abstract: BACKGROUND
  Most genes introduced into phototrophic eukaryotes during the process of endosymbiosis are either lost or relocated into the host nuclear genome. In contrast, groEL homologues are found in different genome compartments among phototrophic eukaryotes. Comparative sequence analyses of recently available genome data, have allowed us to reconstruct the evolutionary history of these genes and propose a hypothesis that explains the unusual genome distribution of groEL homologues.
  
  
  RESULTS
  Our analyses indicate that while two distinct groEL genes were introduced into eukaryotes by a progenitor of plastids, these particular homologues have not been maintained in all evolutionary lineages. This is of significant interest, because two chaperone proteins always co-occur in oxygenic photosynthetic organisms. We infer strikingly different lineage specific processes of evolution involving deletion, duplication and targeting of groEL proteins.
  
  
  CONCLUSIONS
  The requirement of two groEL homologues for chaperon function in phototrophs has provided a constraint that has shaped convergent evolutionary scenarios in divergent evolutionary lineages. GroEL provides a general evolutionary model for studying gene transfers and convergent evolutionary processes among eukaryotic lineages.
authors.affiliation: Allan Wilson Centre for Molecular Ecology and Evolution, Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand. zauner@staff.uni-marburg.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Zauner
authors.forename: Peter
authors.initials: P
authors.lastname: Lockhart
authors.forename: Bettina
authors.initials: B
authors.lastname: Stoebe-Maier
authors.forename: Paul
authors.initials: P
authors.lastname: Gilson
authors.forename: Geoffrey I
authors.initials: GI
authors.lastname: McFadden
authors.forename: Uwe G
authors.initials: UG
authors.lastname: Maier
mesh_terms: D018834:Chaperonin 60 / Q000235:genetics*; D000458:Cyanobacteria / Q000235:genetics*; D019143:Evolution, Molecular; D020440:Gene Duplication; D022761:Gene Transfer, Horizontal; D008957:Models, Genetic; D010788:Photosynthesis; D010802:Phylogeny; D018087:Plastids / Q000235:genetics; D013559:Symbiosis
chemical_list: D018834:Chaperonin 60