Characterization of a plant-stimulated nuclease from Fusarium solani

A unique nuclease is released by Fusarium solani f. spp. pisi and phaseoli macroconidia during germination on pea pod endocarp tissue. This Fsp nuclease is produced in greater amounts by macroconidia germinating on pea pods than in Vogel's rich medium or in water. We have characterized the enzymatic activities, and physical properties of this enzyme. Fsp nuclease makes randomly situated single stranded nicks in single- or double-stranded DNA, leaving a 5' phosphate group and a 3' hydroxyl group on the nicked DNA strand. This nicking activity is stimulated by divalent cations over a range of 2 10 mM, with Mn²⁺ > Ca²⁺ > Co²⁺ > Mg²⁺. Zinc inhibited the nuclease, even in the presence of stimulatory divalent cations. Fsp nuclease is susceptible to treatment with proteinase K or SDS, indicating a proteinaceous identity, but surprisingly, is resistant to boiling. A 22 kDa molecular weight was estimated by renaturing the enzyme following denaturing electrophoresis. The possible role of this nuclease in virulence is being investigated. Copyright 1993, 1999 Academic Press