C-terminal propeptide of the Caldariomyces fumago chloroperoxidase : an intramolecular chaperone?

The Caldariomyces fumago chloroperoxidase (CPO) is synthesised as a 372-aa precursor which undergoes two proteolytic processing events: removal of a 21-aa N-terminal signal peptide and of a 52-aa C-terminal propeptide. The Aspergillus niger expression system developed for CPO was used to get insight into the function of this C-terminal propeptide. A. niger transformants expressing a CPO protein from which the C-terminal propeptide was deleted failed in producing any extracellular CPO activity, although the CPO polypeptide was synthesised. Expression of the full-length gene in an A. niger strain lacking the KEX2-like protease PclA also resulted in the production of CPO cross-reactive material into the culture medium, but no CPO activity. Based on these results, a function of the C-terminal propeptide in CPO maturation is indicated. © 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved. Molecular Sequence Numbers: GENBANK: AJ300448, X04486; Chemicals/CAS: Chloride Peroxidase, EC 1.11.1.10; DNA Primers; Enzyme Precursors; Molecular Chaperone