Cloning and sequencing of a gene for Mucor rennin, an aspartate protease from Mucor pusillus.

The aspartate protease of Mucor pusillus (Mucor pusillus rennin; MPR) is a milk-clotting enzyme used in the cheese industry. The partial amino acid sequence of MPR was determined and oligonucleotide probes were synthesized for cloning of the MPR gene. A clone giving positive hybridization with the probes was selected from the cosmid library. Sequencing of the cloned DNA revealed an open reading frame of 1281 bp without introns which encodes 361 amino acids for the expected MPR with an NH2-terminal extension of 66 amino acids. MPR seems to be synthesized as a prepro enzyme.