Tracking the connection between evolutionary and functional shifts using the fungal lipase/feruloyl esterase A family.
BACKGROUND
There have been many claims of adaptive molecular evolution, but what role does positive selection play in functional divergence? The aim of this study was to test the relationship between evolutionary and functional shifts with special emphasis on the role of the environment. For this purpose, we studied the fungal lipase/feruloyl esterase A family, whose functional diversification makes it a very promising candidate.


RESULTS
The results suggested functional shift following a duplication event where neofunctionalisation of feruloyl esterase A had occurred with conservation of the ancestral lipase function. Evolutionary shift was detected using the branch-site model for testing positive selection on individual codons along specific lineages. Positively selected amino acids were detected. Furthermore, biological data obtained from site-directed mutagenesis experiments clearly demonstrated that certain amino acids under positive selection were involved in the functional shift. We reassessed evolutionary history in terms of environmental response, and hypothesized that environmental changes such as colonisation by terrestrial plants might have driven adaptation by functional diversification in Euascomycetes (Aspergilli), thus conferring a selective advantage on this group.


CONCLUSIONS
The results reported here illustrate a rare example of connection between fundamental events in molecular evolution. We demonstrated an unequivocal connection between evolutionary and functional shifts, which led us to conclude that these events were probably linked to environmental change.
Levasseur
Anthony
A
Phylogenomics Laboratory, EA 3781 Evolution Biologique Université de Provence, Case 19, Pl, V, Hugo, 13331 Marseille Cedex 03, France. Anthony.Levasseur@up.univ-mrs.fr
Gouret
Philippe
P
Lesage-Meessen
Laurence
L
Asther
Michèle
M
Asther
Marcel
M
Record
Eric
E
Pontarotti
Pierre
P
D000596:Amino Acids / Q000737:chemistry; D001230:Aspergillus / Q000201:enzymology*; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics; D003062:Codon; D019143:Evolution, Molecular; D008049:Lipase / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D013997:Time Factors
D000596:Amino Acids; D003062:Codon; D011506:Proteins; D002265:Carboxylic Ester Hydrolases; D008049:Lipase; C070196:feruloyl esterase