title: Gene identification and molecular characterization of solvent stable protease from a moderately haloalkaliphilic bacterium, Geomicrobium sp. EMB2.
abstract: Cloning and characterization of the gene encoding a solvent-tolerant protease from the haloalkaliphilic bacterium Geomicrobium sp. EMB2 are described. Primers designed based on the N-terminal amino acid sequence of the purified EMB2 protease helped in the amplification of a 1,505-bp open reading frame that had a coding potential of a 42.7-kDa polypeptide. The deduced EMB2 protein contained a 35.4-kDa mature protein of 311 residues, with a high proportion of acidic amino acid residues. Phylogenetic analysis placed the EMB2 gene close to a known serine protease from Bacillus clausii KSM-K16. Primary sequence analysis indicated a hydrophobic inclination of the protein; and the 3D structure modeling elucidated a relatively higher percentage of small (glycine, alanine, and valine) and borderline (serine and threonine) hydrophobic residues on its surface. The structure analysis also highlighted enrichment of acidic residues at the cost of basic residues. The study indicated that solvent and salt stabilities in Geomicrobium sp. protease may be accorded to different structural features; that is, the presence of a number of small hydrophobic amino acid residues on the surface and a higher content of acidic amino acid residues, respectively.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India.
authors.forename: Ram
authors.initials: R
authors.lastname: Karan
authors.forename: Raj Kumar Mohan
authors.initials: RK
authors.lastname: Singh
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kapoor
authors.forename: S K
authors.initials: SK
authors.lastname: Khare
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004795:Enzyme Stability; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012997:Solvents
chemical_list: D004269:DNA, Bacterial; D012997:Solvents; D010447:Peptide Hydrolases