Cloning, heterologous expression and structural characterization of an alkaline serine protease from sea water haloalkaliphilic bacterium

Cloning and functional attributes of a serine protease gene from haloalkaliphilic bacteria are described. The protease gene of similar to 1,600 bp amplified from the genomic DNA was cloned into TA vector followed by the sub-cloning into pUC19 for expression. Growth of the organism and gene expression was studied at 30 and 37 degrees C in the presence of 0.5-2.0 mM IPTG. Sequencing of the gene and homology search of the sequence revealed that the gene encoded an extracellular alkaline serine protease belonging to superfamily subtilisin-like hydrolases. The amino acid sequence alignment resulted from the BLAST search of the subtilisin exhibited high sequence homology with the Bacillus subtilis ssp. subtilis strain 168 and subtilisins of other Bacillus sp., B. subtilis and B. mojavensis. The deduced amino acid sequence exhibited a mature protease of a 419 amino acid, single-chained monomeric peptide with the large number of the positively charged amino acids suggesting its hydrophilic nature.