An anti-lipopolysaccharide factor Md-ALF from the Indian flower tail shrimp, Metapenaeus dobsoni: Molecular and phylogenetic characterization

Abstract

Antimicrobial peptides play a crucial role in the innate immune defence mechanism of various organisms. Anti-lipopolysaccharide factors (ALFs) and their derivatives are a type of cationic AMPs which exhibit broad spectrum antimicrobial activities. This study identified and characterized an anti-lipopolysaccharide factor (Md-ALF) from the haemocytes of Indian flower tail shrimp, Metapenaeus dobsoni. The cDNA of Md-ALF consisted of 294 bp with 98 deduced amino acids. The deduced protein sequence possessed a LPS binding domain and shared highest sequence identity with shrimp ALFs. It showed an isoelectric point of 9.76 and a net positive charge of +7. The secondary structure analysis revealed the presence of three helices, four β turns and three β hairpin like structures. In silico analysis revealed that Md-ALF has anti-bacterial, anti-viral, anti-fungal and anti-cancer properties. Phylogenetic analysis revealed the ancestral relationship of Md-ALF with other shrimp ALFs. Molecular and physico- chemical characterization of Md-ALF showed similarity with reported ALFs from other crustaceans, suggesting its possible role in the innate defence mechanism of M. dobsoni.