A new isoform of anti-lipopolysaccharide factor identified from the blue swimmer crab, Portunus pelagicus: Molecular characteristics and phylogeny

Abstract

Anti-lipopolysaccharide factors are small proteins that bind and neutralize lipopolysaccharide and exhibit potent antimicrobial activities. This study presents the molecular characterization and phylogenetic analysis of the first ALF isoform (Pp-ALF1; JQ745295) identified from the hemocytes of Portunus pelagicus. The full length cDNA of Pp-ALF1 consisted of 880 base pairs encoding 293 amino acids with an ORF of 123 amino acids and contains a putative signal peptide of 24 amino acids. Pp-ALF1 possessed a predicted molecular weight (MW) of 13.86 kDa and theoretical isoelectric point (pI) of 8.49. Two highly conserved cysteine residues and putative LPS binding domain were observed in Pp-ALF1. Peptide model of Pp-ALF1 consisted of two α-helices crowded against a four-strand β-sheet. Comparison of amino acid sequences and neighbor joining tree showed that Pp-ALF1 has a maximum similarity (46%) to ALF present in Portunus trituberculatus followed by 39% similarity to ALF of Eriocheir sinensis and 38% similarity to ALFs of Scylla paramamosain and Scylla serrata. Pp-ALF1 is found to be a new isoform of ALF family and its characteristic similarity with other known ALFs signifies its role in protection against invading pathogens.

Two isoforms of anti-lipopolysaccharide factors identified and characterized from the hemocytes of portunid crabs, Portunus pelagicus and Scylla tranquebarica

“…This study reports for the first time an ALF isoform from S. tranquebarica designated as StALF (JQ899453). The study also reports the second ALF isoform from P. pelagicus, designated as PpALF2 (JQ899452) to distinguish PpALF1 (JQ745295) identified in our previous study (Afsal et al, 2012).…”

“…Reports on crustacean ALFs have been increasing in recent years viz., in shrimps (Tharntada et al, 2008); crabs (Afsal et al, 2011(Afsal et al, , 2012; lobsters (Beale et al, 2008) and crayfishes (Sun et al, 2011). Some decapods have also been reported to express multiple ALF isoforms which vary in length or sequence and display different biological activities.…”

The Role of Biophysical Parameters in the Antilipopolysaccharide Activities of Antimicrobial Peptides from Marine Fish

“…Nonetheless, the diagram in Figure 1 shows that the LPS binding domains of both PpALF 2 and StALF are displaying cationicity, hydrophobicity and clustering of the cationic and hydrophobic motifs which are attributable to peptide’s amphipathic character. In addition, given their high similarity to other ALFs, the structural model of PpALF2 and StALF created using the SWISS-MODEL server consisted of two α-helices crowded against a four-strand β-sheet, like PpALF1 [ 39 ]. Importantly, an amphipathic loop is formed from the LPS binding domain situated between two β-strands [ 40 ].…”

Molecular Characterization and Phylogenetic Analysis of Novel Isoform of Anti-lipopolysaccharide Factor from the Mantis Shrimp, Miyakea nepa

“…Antilipopolysaccharide factor is a cationic AMP which constitutes one of the key effector molecules in the innate immune system of crustaceans and is capable of binding and neutralizing lipopolysaccharides (LPSs). The first ALF was identified from the amebocyte of the horseshoe crab Limulus polyphemus [5], and later numerous ALFs were identified and characterized from decapod crustaceans including penaeid shrimps [6][7][8][9], non-penaeid shrimps [10], lobsters [11], crabs [12][13][14][15] and crayfish [16]. Structure of ALF was elucidated using NMR and found & Rosamma Philip rosammap@gmail.com; rose@cusat.ac.in that it consists of three a-helices packed against a fourstranded b-sheet [17,18].…”