Gene cloning, expression and characterization of a novel cold-adapted protease from Planococcus sp.

•A novel protease gene, cpls8, was cloned from the newly isolated bacterium and successfully expressed in Escherchia coli.•The heterologously expressed CPLS8 exhibited optimal activity at pH 10.0 and demonstrated an increasing activity at temperatures between 5 and 35 °C with a complete inactivation at 55 °C.•Compared with other cold-adapted proteases, the CPLS8 was more resistant to the detergent of SDS, which can keep more than 80% of the highest activity in the presence of SDS (1.0%), even the concentration of SDS is 3.0%, more than 19% of its initial activity was still retained.•CPLS8 was a novel cold-adapted protease and seemed to be attractive for industrial application.

A psychrophilic bacterium strain named M7 was isolated from the deep-sea mud of Eastern Indian Ocean and identified as Planococcus sp. A novel protease gene, cpls8, was cloned from the newly isolated bacterium and successfully expressed in Escherchia coli. The open reading frame of cpls8 gene encodes a 329-amino acid polypeptide with a molecular weight of approximately 35.6 kDa. Sequence alignment reveals that the CPLS8 protease contains a catalytic module belonging to serralysin-type protease family 8 and displays the highest identity of 62% to a functionally known protease from Bacillus sp. The heterologously expressed CPLS8 exhibited optimal activity at pH 10.0 and demonstrated an increasing activity at temperatures between 5 and 35 °C with a complete inactivation at 55 °C. At 25 °C the relative activity of CPLS8 still reached to 80% of the highest activity at 35 °C. These enzymatic properties together with amino acid composition analysis showed that CPLS8 was a novel cold-adapted protease and seemed to be attractive for industrial application.

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