Detection and characterization of protease secreted by the plant pathogen Xylella fastidiosa

Abstract

Xylella fastidiosa is a pathogenic bacterium found in several plants. These bacteria secrete extracellular proteases into the culture broth as visualized in sodium-dodecyl-sulfate polyacrylamide activity gels 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 9,713 produced two bands of approximately 84 and 64 kDa. These organisms produced zones of hydrolysis in agar plates amended with gelatin, casein and hemoglobin. Gelatin was the best substrate for these proteases. Sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE) activity gel 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.

A genomic survey of proteases in Aspergilli

“…Proteases form a complex family of enzymes that possess different catalytic mechanisms with various active sites and divergent substrate specificities [1, 2]. Proteases hydrolyze peptides in aqueous environments [3, 4] and for years this ability has been utilized in industrial processes like food processing, waste treatment, textiles/detergent applications, and photography/chemical processing [5–9].…”

“…Proteases hydrolyze peptides in aqueous environments [3, 4] and for years this ability has been utilized in industrial processes like food processing, waste treatment, textiles/detergent applications, and photography/chemical processing [5–9]. Proteases can be classified into four major groups: aspartic, cysteine, metallo and serine proteases [2]. Protease inhibitors for each of these classes have been described [10].…”

Sugarcane glycoproteins are required to the production of an active UDP-glucose dehydrogenase byXanthomonas albilineans

“…Xylella fastidiosa, another pathogenic bacterium of plants producing xanthan-like gums (Da Silva et al, 2001), also synthesized extracellular proteases into the culture broth. These proteases produced by strains of Xylella fastidiosa from citrus and grape, belong to the serine-and metallo-protease group, respectively (Fedatto et al, 2006). Dow et al (1990) reported that proteases could be used to degrade protein in the plant cell wall, allowing bacterial spread or overcome host defences.…”

In vitro Determination of Extracellular Proteins from Xylella fastidiosa

“…These pit membranes are composed of cellulose, hemicellulose, pectin, lignin, and proteins (Fry et al, 1994). Previous studies have associated the participation of secreted proteins, such as serine and metallo-protease, endo-1,4-β-glucanase and polygalacturonase with pit membrane degradation, which facilitates the crossing of these membranes by X. fastidiosa to reach adjacent vessels (Fedatto et al, 2006; Pérez-Donoso et al, 2010). In addition to secretion systems, Gram-negative bacteria exhibit outer membrane vesicles (OMVs) that serve as secretory vehicles for proteins and lipids (Kuehn and Kesty, 2005; Tseng et al, 2009; Costa et al, 2015).…”