Biochemical characterization of MI-ENG1, a family 5 endoglucanase secretedby the root-knot nematode Meloidogyne incognita

A beta-1,4-endoglucanase named MI-ENG1, homologous to the family 5 glycosid e hydrolases, was previously isolated from the plant parasitic root-knot ne matode Meloidogyne incognita. We describe here the detection of the enzyme in the nematode homogenate and secretion and its complete biochemical chara cterization. This study is the first comparison of the enzymatic properties of an animal glycoside hydrolase with plant and microbial enzymes. MI-ENG1 shares many enzymatic properties with known endoglucanases from plants, fr ee-living or rumen-associated microorganisms and phytopathogens. In spite o f the presence of a cellulose-binding domain at the C-terminus, the ability of MI-ENG1 to bind cellulose could not be demonstrated, whatever the exper imental conditions used. The biochemical characterization of the enzyme is a first step towards the understanding of the molecular events taking place during the plant-nematode interaction.