Differential gene transfers and gene duplications in primary and secondary endosymbioses.
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.
Zauner
Stefan
S
Allan Wilson Centre for Molecular Ecology and Evolution, Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand. zauner@staff.uni-marburg.de
Lockhart
Peter
P
Stoebe-Maier
Bettina
B
Gilson
Paul
P
McFadden
Geoffrey I
GI
Maier
Uwe G
UG
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
D018834:Chaperonin 60