title: Characterization of PG2, an early endoPG produced by Sclerotinia sclerotiorum, expressed in yeast.
abstract: Sclerotinia sclerotiorum, a plant pathogenic ascomycete, contains a neutral endopolygalacturonase (endoPG) subfamily of genes that was previously isolated. We report here that pg2, a member of this subfamily, is early and strongly expressed during the first steps of pathogenesis of sunflower cotyledons. The corresponding protein, PG2, was produced in the heterologous Kluyveromyces lactis system and purified. Characterization of the recombinant enzyme revealed a narrow pH activity curve with an optimal pH of 4.5. Hydrolysis of polygalacturonic acid by PG2 resulted in the accumulation of oligomers ranging from 2- to 9-mer. This degradation profile indicates a random attack on the polymer and demonstrates an endo-mode of action. These results provide evidence that pg2 contributes to the infection process during the early phase of host colonization.
authors.affiliation: Laboratoire de Biologie Cellulaire Fongique, UMR 5122 CNRS INSA UCB, Bat Lwoff, 10 rue Dubois, Université Claude Bernard Lyon 1, 69622 Villeurbanne Cedex, France. cotton@biomserv.univ-lyon1.fr
authors.forename: Pascale
authors.initials: P
authors.lastname: Cotton
authors.forename: Christine
authors.initials: C
authors.lastname: Rascle
authors.forename: Michel
authors.initials: M
authors.lastname: Fevre
mesh_terms: D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics; D015152:Blotting, Northern; D002855:Chromatography, Thin Layer; D015966:Gene Expression Regulation, Fungal; D006368:Helianthus / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007716:Kluyveromyces / Q000235:genetics; D010368:Pectins / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D011096:Polygalacturonase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D011994:Recombinant Proteins; D010368:Pectins; D011096:Polygalacturonase; C003181:polygalacturonic acid