Bright Singh, I S; Rosamma, Philip; Sanjeevan, V N; Swapna, Antony P; Afsal, V V; Anil Kumar, P R(Elsevier, May 26, 2012)
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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.