Roles of the N- and C- terminal pro-sequences of aqualysin I precursor in the processing and extracellular secretion of the enzyme.

Abstract

Aqualysin I is a subtilisin-type, heat-stable protease, which is secreted extracellularly by Thermus aquaticus YT-1, an extremely thermophilic, Gram-negative bacterium1–3. The enzyme contains two disulfide bonds4, which seem to be the cause of its heat stability. Aqualysin I is produced as a large precursor consisting of four structurally distinguishable domains; an N-terminal signal peptide (14 amino acid residues), an N-terminal pro-sequence (113 residues), the protease domain (281 residues) and a C-terminal pro-sequence (105 residues)5.