Production and Extracellular Secretion of Aqualysin I (a Thermophilic Subtilisin-Type Protease) in a Host-Vector System for Thermus thermophilus.

Aqualysin I is synthesized as a large precursor, processed, and secreted into the culture medium by Thermus aquaticus YT-1. An expression plasmid for the aqualysin I gene in T. thermophilus HB27 was constructed. T. thermophilus cells harboring the recombinant plasmid produced correctly processed aqualysin I, and the mature enzyme was secreted into the culture medium.