Degradation of host components by a metallopeptidase of Cryptococcus neoformans

Proteolytic activities were detected in a cytosoluble 100 000 g extract of Cryptococcus neoformans using 7-amido-4-methylcoumarin substrates. The main proteolytic activity cleaved the L-arginine-AMC substrate. This protease was purified by high performance liquid chromatography and had a molecular weight of 80 kDa as demonstrated by SDS-PAGE in the presence of reducing conditions. The enzyme was inhibited by EDTA and o -phenanthroline which are metallopeptidase inhibitors. The protease displayed high enzymatic activity between pH 5.8 and 7, and its pl was localised at pH 5.04. Furthermore, this metallopeptidase was not secreted in culture supernatants, but was able to degrade partially or totally some of the extracellular matrix components, as fibronectin or laminin, and host lgG.