ISOLATION AND CHARACTERIZATION OF THE GENE ENCODING A NOVEL, THERMOSTABLE SERINE PROTEINASE FROM THE MOLD TRITIRACHIUM-ALBUM LIMBER

A number of proteinases are induced and secreted into the culture medium of Tritirachium album Limber when the nitrogen source is limited to exogenous proteins. We have constructed a cDNA library using the polyadenylated RNA isolated during the nutritional induction with bovine serum albumin. A full‐length clone of a gene for a new proteinase (named proteinase R) was identified from this library. This clone contained sequences coding for the 108‐amino‐acid prepro‐leader as well as for the 279‐amino‐acid mature preoteinase. Proteinase R apparently belongs to the subtilisin group of serine proteases that contains disulphide bonds. Homology between proteinase R and proteinase K was found to be about 87% at the nucleotide as well as at the amino acid level. The Brookhaven Protein Data Base co‐ordinate file of proteinase K was used as a template to study the proteinase R substitutions in three‐dimensional space. The majority of the substitutions of proteinase R with respect to proteinase K were found to be on the exterior of the protein model. Copyright © 1990, Wiley Blackwell. All rights reserved