STRUCTURE AND FUNCTION OF A FAMILY OF CHITINASE ISOZYMES FROM BRUGIANMICROFILARIAE

A family of chitinase isozymes, consisting of three proteins from the microfilariae of Brugia pahangi and two previously described chitinase s from the microfilariae of B. malayi, has been characterized. The fiv e members of this family display closely related chitin-degrading acti vities, characterized by strong endo- rather than exochitinase activit y. All five proteins have highly conserved sequences at their amino-te rmini and appear to share a two-domain tertiary structure, as demonstr ated by proteolysis of the native molecules. The aminoterminal domain appears to be responsible for the enzymatic activity and retains this activity when cleaved and separated from the remainder of the molecule (s). Glycosylation differences are apparent for the isozymes from the two different Brugian species. No representatives of this family could be detected in the microfilariae of another filarial species, Dirofil aria immitis, which differs in several aspects of its lifestyle from t he Brugian filariae. (C) 1995 Academic Press, Inc.