aspS encoding an unusual aspartyl protease from Sclerotinia sclerotiorum is expressed during phytopathogenesis

The gene aspS encoding an aspartyl protease has been cloned from Sclerotini a sclerotiorum by screening a genomic library with a PCR-amplified fragment of the gene. The open reading frame of 1368 bp interrupted by one intron w ould encode a preproprotein of 435 amino acids. The catalytic aspartyl resi dues characteristic of aspartyl proteases are conserved; however, the activ e-site motif (DSG) in the N-terminal lobe is unusual in that Ser replaced T hr used in the active-site motif (DTG) of the C-terminal lobe and in all ot her fungal aspartyl proteases. RT-PCR revealed that aspS expression in axen ic culture is not subjected to catabolite repression and demonstrated that aspS is expressed from the beginning of infection of sunflower cotyledons. (C) 2001 Federation of European Microbiological Societies. Published by Els evier Science B.V. All rights reserved.