Characterization of a metagenomic serine metalloprotease and molecular docking studies

Abstract

Functional screening of marine metagenomic library resulted in a single protease positive clone (GUSK-1) containing a 4.0 kbps insert. The DNA insert was sub-cloned using pET-22b expression vector system. Phenylmethylsulfonyl fluoride (PMSF) caused 28% inhibition of protease activity, while 60% inhibition was observed with Disodium ethylenediaminetetraacetic acid (EDTA-Na2) suggesting it to be a serine metalloprotease. The pH and temperature optima for protease activity were found to be 10 and 70 °C. Bivalent metal cations such as Mg2+, Fe2+, Mn2+, and Ca2+ enhanced the protease activity indicating their possible role either at the catalytic site or in the stabilization of the enzyme. Additionally, common organic solvents viz. isopropanol, ethanol, methanol, butanol, chloroform, and benzene also improved the protease activity. Sequence analysis of the DNA insert demonstrated an open reading frame (ORF) of 861 bps encoding 286 amino acids corresponding to a protease belonging to transpeptidase superfamily. In silico docking revealed interesting interactions of this serine metalloprotease with a gp41 protein of HIV-1 and cell adhesion protein of Listeria monocytogenes. Therefore, the novel characteristics of this protease make it a potential candidate for various biotechnological and pharmaceutical industries. © 2018 Elsevier Ltd