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.

Hemolymph proteins in marine crustaceans

“…Crustins have antibacterial properties, they must contribute to a greater or lesser extent in defence against bacterial infections, at least in decapods. However, the variable pattern in their expression after bacterial challenge is unlike than known for other arthropod antimicrobial peptides [33] .…”

A Brief Review on the Antioxidants and Antimicrobial Peptides Revealed in Mud Crabs from the Genus of Scylla

“…The recombinant CrusSp was produced to assess its antimicrobial activities against Gram-negative bacteria, with the indication that CrusSp may be involved in the innate immunity of S. paramamosain. Interestingly, Afsal et al [37] successfully identified a new isoform of ALF, Sc-ALF, and first crustin, Sc-crustin, from the haemocyte of the S. serrata. On top of that, the nucleotides sequence of Sc-ALF was found to be 100% similar to ALF in S. paramamosain, which is almost similar to several AMP from other decapods crustaceans when tested with BLAST analysis.…”

Molecular characterization and phylogenetic analysis of an anti-lipopolysaccharide factor from the crucifix crab, Charybdis feriatus

“…2 Since then, numerous ALF homologs have been identified and characterized from decapod crustaceans, including penaeid shrimp, [3][4][5][6] nonpenaeid shrimp, 7 lobsters, 8,9 crabs, and crayfish. [10][11][12][13] ALFs belong to the group of single-domain AMPs with a signal peptide at the N-terminal region followed by a conserved LPS-binding domain.…”