title: Deletion of the SNP1 trypsin protease from Stagonospora nodorum reveals another major protease expressed during infection.
abstract: The wheat fungal pathogen Stagonospora nodorum produces an extracellular trypsin-like protease, SNP1, during early stages of hyphal growth on the surface of host leaves and during penetration. Variation of SNP1 mRNA levels and enzyme activity during infection, were correlated with levels of aggressiveness of three wild-type isolates. SNP1 was deleted in two wild-type isolates using a gene replacement strategy. SNP1-deleted mutants completely lacked trypsin activity in vitro and on inoculated wheat leaves, but were not reduced in pathogenicity. SNP1-deleted mutants still have 50% of the total alkaline protease activity of wild-type. This residual activity comes from a previously undetected alkaline protease with subtilisin-like substrate and inhibitor specificities, which is produced in vitro and on host leaves. We hypothesize that this subtilisin protease may act in concert with SNP1 and may compensate for the loss of trypsin protease activity in the SNP1-deletion mutants.
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: Laurence V
authors.initials: LV
authors.lastname: Bindschedler
authors.forename: Pedro
authors.initials: P
authors.lastname: Sanchez
authors.forename: Steven
authors.initials: S
authors.lastname: Dunn
authors.forename: Jose
authors.initials: J
authors.lastname: Mikan
authors.forename: Madan
authors.initials: M
authors.lastname: Thangavelu
authors.forename: John M
authors.initials: JM
authors.lastname: Clarkson
authors.forename: Richard M
authors.initials: RM
authors.lastname: Cooper
mesh_terms: D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D015152:Blotting, Northern; D015139:Blotting, Southern; D010450:Endopeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017353:Gene Deletion; D015870:Gene Expression; D066298:In Vitro Techniques; D010935:Plant Diseases / Q000382:microbiology; D012697:Serine Endopeptidases / Q000235:genetics*; D014170:Transformation, Genetic; D014908:Triticum / Q000382:microbiology*; D014774:Virulence
chemical_list: D010450:Endopeptidases; C409688:SNP1 protein, Phaeosphaeria nodorum; D012697:Serine Endopeptidases