Integration of evolutionary and desolvation energy analysis identifies functional sites in a plant immunity protein.
Plant immune responses often depend on leucine-rich repeat receptors that recognize microbe-associated molecular patterns or pathogen-specific virulence proteins, either directly or indirectly. When the recognition is direct, a molecular arms race takes place where plant receptors continually and rapidly evolve in response to virulence factor evolution. A useful model system to study ligand-receptor coevolution dynamics at the protein level is represented by the interaction between pathogen-derived polygalacturonases (PGs) and plant polygalacturonase-inhibiting proteins (PGIPs). We have applied codon substitution models to PGIP sequences of different eudicotyledonous families to identify putative positively selected sites and then compared these sites with the propensity of protein surface residues to interact with protein partners, based on desolvation energy calculations. The 2 approaches remarkably correlated in pinpointing several residues in the concave face of the leucine-rich repeat domain. These residues were mutated into alanine and their effect on the recognition of several PGs was tested, leading to the identification of unique hotspots for the PGIP-PG interaction. The combined approach used in this work can be of general utility in cases where structural information about a pattern-recognition receptor or resistance-gene product is available.
Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia Vegetale, Università di Roma La Sapienza, 00185 Rome, Italy.
Manuela
M
Casasoli
Luca
L
Federici
Francesco
F
Spinelli
Adele
A
Di Matteo
Nicoletta
N
Vella
Flavio
F
Scaloni
Juan
J
Fernandez-Recio
Felice
F
Cervone
Giulia
G
De Lorenzo
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D003062:Codon / Q000235:genetics; D004734:Energy Metabolism; D019143:Evolution, Molecular; D007109:Immunity; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011096:Polygalacturonase / Q000378:metabolism*; D020539:Sequence Analysis, Protein
D003062:Codon; C081479:PGIP protein, plant; D010940:Plant Proteins; D011096:Polygalacturonase