title: Molecular characterization and phylogenetic analysis of two antimicrobial peptides: Anti-lipopolysaccharide factor and crustin from the brown mud crab, Scylla serrata.
abstract: AMPs are evolutional weapons, widely used by animals and plants in their innate immune system to fend off invading microbes. The present study reports characterization of a new ALF isoform (Sc-ALF; HQ638024) and the first crustin (Sc-crustin; HQ638025) from the mud crab, Scylla serrata. The full-length cDNA of Sc-ALF consisted of 477 bp with an ORF of 123 amino acids and a putative signal peptide of 26 amino acids. Sc-ALF had a predicted molecular weight (MW) of 11.17 kDa and theoretical isoelectric point (pI) of 9.95. Two highly conserved cysteine residues and putative LPS binding domain were observed in Sc-ALF. Comparison of amino acid sequences with neighbor-joining tree indicated that Sc-ALF shared maximum similarity with ALF of S. paramamosain. Peptide model of Sc-ALF created using SWISS-MODEL server was found to consist of two α-helices crowded against a four-strand β-sheet. The full-length cDNA of Sc-crustin consisted of 433 base pairs with an ORF of 111 amino acids and a putative signal peptide of 21 amino acids. Comparison of amino acid sequences with a neighbor-joining tree revealed that Sc-crustin shared high identity with other known crustins characterized from S. paramamosain, P. trituberculatus, H. araneus, C. maenas and F. chinensis. A whey-acidic-protein domain could be detected at the C-terminus with the characteristic four disulfide core. Sc-crustin had a predicted MW of 10.24 kDa and a pI of 8.76. Peptide model of Sc-crustin created using SWISS-MODEL server indicated a random coiled structure that is with two possible β-sheets but no helices.
authors.affiliation: Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology (CUSAT), Fine Arts Avenue, Kochi 682 016, Kerala, India.
authors.forename: V V
authors.initials: VV
authors.lastname: Afsal
authors.affiliation: Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology (CUSAT), Fine Arts Avenue, Kochi 682 016, Kerala, India.
authors.forename: Swapna P
authors.initials: SP
authors.lastname: Antony
authors.affiliation: Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology (CUSAT), Fine Arts Avenue, Kochi 682 016, Kerala, India.
authors.forename: Naveen
authors.initials: N
authors.lastname: Sathyan
authors.affiliation: Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology (CUSAT), Fine Arts Avenue, Kochi 682 016, Kerala, India.
authors.forename: Rosamma
authors.initials: R
authors.lastname: Philip
keywords: Anti-lipopolysaccharide factor; Antimicrobial peptide; Crustin; Innate immunity; Scylla serrata