Detection and characterization of protease secreted by the plant pathogen Xylella fastidiosa
Fedatto, Luciana Maria; Silva-Stenico, Maria Estela; Etchegaray, Augusto; Pacheco, Flavia T. H.; Rodrigues, Jorge L. M.; Tsai, Siu Mui
Xylella fastidiosa is a pathogenic bacterium found in several plants. These bacteria secrete extracellular proteases into the culture broth as visualized in sodium-dodecytsulfate potyacrytamide activity gets containing gelatin as a copolymerized substrate. Three major protein bands were produced by the citrus strain with molar masses (MM) of 122, 84 and 65 kDa. Grape strain 9713 produced two bands of approximately 84 and 64kDa. These organisms produced zones of hydrolysis in agar plates amended with getatin, casein and hemogtobin. Gelatin was the best substrate for these proteases. Sodium dodecyl sulfate-polyacrylamide etectrophoresis (SDS-PAGE) activity get indicated that the protease of Xylella fastidiosa from citrus and grape were completely inhibited by PMSF and partially inhibited by EDTA. The optimal temperature for protease activity was 30 degrees C with an optimal pH of 7.0. Among the proteolytic enzymes secreted by the phytopathogen, chitinase and beta-1,3-glucanase activities were also detected in cultures of Xylella fastidiosa (citrus). From these results, it is suggested that proteases produced by strains of Xylella fastidiosa from citrus and grape, belong to the serine- and metallo-protease group, respectively.