The Aspergillus nidulans pyrG89 mutation alters glycosylation of secreted acid phosphatase

The glycosylation level of the pacA-encoded acid phosphatase secreted by As pergillus nidulans was reduced in strains pabaA1 pyroA4 and pabaA1 pyroA4 p yrG89, compared to strains carrying these mutations singly. The molecular m ass of the enzyme secreted by the triple mutant grown at pH 5.0 was 105 and 45 kDa as determined by exclusion chromatography and SDS-PAGE, respectivel y. In contrast, the pabaA1 strain secreted acid phosphatases of 119 and 62 kDa, The enzyme also had an altered electrophoretic mobility and glycosylat ion had a protective effect against its heat inactivation. Thus, this combi nation of mutants alters glycosylation of the enzyme, leading to changes in their structural properties. In spite of this, no deviation was observed i n the apparent optimum pH and Michaelis kinetics for enzymatic hydrolysis o f p-nitrophenyl phosphate or alpha -naphthyl phosphate, (C) 2001 Academic P ress.