title: Evidence that cleavage of the precursor enzyme by autocatalysis caused secretion of multiple amylases by Aspergillus niger.
abstract: The observation that a mutant strain of Aspergillus niger isolated for protease overproduction accumulated Taka-amylase supported an earlier report that processing of the precursor amylase by protease resulted in the secretion of multiple amylases. Studies using a mutant strain revealed that such processing was not due to aspergillopepsin but to autocatalysis by an inherent protease activity of the precursor and glucoamylase. Alignment of protease sequences with glucoamylase showed regions of consensus with serine carboxypeptidase of A. niger. Thus point mutations in this region due to ultraviolet radiation apparently caused the mutant to evolve with enhanced protease activity that degraded the precursor and accumulated Taka-amylase.
authors.affiliation: Department of Food Microbiology, Central Food Technological Research Institute, Mysore 570013, India.
authors.forename: K
authors.initials: K
authors.lastname: Ravi-Kumar
authors.forename: K S
authors.initials: KS
authors.lastname: Venkatesh
authors.forename: S
authors.initials: S
authors.lastname: Umesh-Kumar
mesh_terms: D000681:Amylases / Q000302:isolation & purification / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology* / Q000502:physiology; D002384:Catalysis; D004792:Enzyme Precursors / Q000378:metabolism*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D013172:Spores, Fungal / Q000502:physiology
chemical_list: D004792:Enzyme Precursors; D007527:Isoenzymes; D000681:Amylases