Partial characterization of polygalacturonase from Fusarium graminearum

KIKOT, G.E.; ROJAS, N.L.; HOURS, R.A.; ALCONADA, T.M.

Mar del Plata

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Properties of ecosystems are influential in the reduction of plant host cell-wall integrity by pathogen virulence factors. Phytopathogenic fungi are able to secrete lytic enzymes as virulence factors. Among them, pectinases are one of the most important biocatalysts. F. graminearum is the causal agent of the Fusarium head-blight (FHB), a destructive disease of wheat. F. graminearum isolates from different agroecological regions were cultivated in a medium with 2.5 g/l glucose, 1.25 g/l citrus pectin, 1.25 g/l oat bran and salts, for 2 weeks. An isolate from Marcos Juarez, Argentina, showed the highest levels of polygalacturonase (PGase) activity, at 48 h of culture. PGase was highly active from pH 3 to 5.5, and between 40 and 50ºC, being the optimum pH and temperature 4.5 and 50ºC, respectively. The enzyme was stable from pH 3.5 to 6.5, at 40ºC. Different metal ions (10 mM) were tested on PGase activity, increasing inhibition was observed as follows: Mg2+ < Mn2+ < Co2+ < Zn2+ < Cu2+ < Ca2+ < Ba2+ < Hg2+. Ion-exchange chromatography was carried out by FPLC with a HiTrap SP anion-exchange column. PGase activity was eluted in a single sharp peak and overlapped with the protein peak. Despite the fact that biological function of PGases are controversial related to plant-pathogen interaction, it is considered as an important parameter in these kinds of interactions.