Detalle de: 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.