Identification of a member of the serralysin family isolated from a psychrotrophic bacterium, Pseudomonas fluorescens 114

An extracellular metalloprotease named No.114 protease is one of the major secretions of a psychrotrophic bacterium, Pseudomonas fluorescens 114, the cold-adaptation mechanism of which has not been identified. In this study, we purified and cloned No.114 protease, which is a single polypeptide havin g a molecular mass of 47 kDa. This protease contains a zinc-binding motif ( HEXXHUXUGUXH: X, arbitrary amino acid; U, bulky hydrophobic amino acid), gl ycine-rich repeats (GGXGXD) and no cysteine residue, which are the features specifically found in serralysin subfamily. No.114 protease has its maximu m activity at the temperature of 35-40 degrees C, which is about 20 degrees C lower than that of a serralysin from a mesophilic bacterium, Pseudomonas aeruginosa. All these results imply that No.114 protease from this psychro philic bacterium is a unique member of the serralysin group characterized b y a low optimal temperature.