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

Abstract

a b s t r a c tAnti-lipopolysaccharide factors (ALFs), a type of cationic antimicrobial peptides (AMPs), and their derivatives are becoming predominant candidates for potential drugs in viral and bacterial diseases. This study reports the first ALF from the mud crab Scylla tranquebarica (StALF, JQ899453) and the second ALF isoform from the blue swimmer crab Portunus pelagicus (PpALF2, JQ899452). Both sequences encoded for precursor molecules, starting with a signal peptide containing 26 amino acid residues, followed by a highly cationic mature peptide, containing two conserved cysteine residues flanking a putative lipopolysaccharide (LPS)-binding domain. BLAST analysis revealed that both PpALF2 and StALF exhibited significant similarity with crustacean ALF sequences. The predicted molecular mass of the mature ALFs was 11.2 kDa with an estimated pI of 10.0. PpALF2 and StALF also showed the typical pattern of alternating hydrophobic and hydrophilic residues in their putative disulphide loop, suggesting that they comprise the same functional domain. Phylogenetic analysis showed that PpALF2 and StALF have similar evolutionary status and they were phylogenetically ancient immune effector molecules which may play an essential role in the host defense mechanism. The spatial structures of PpALF2 and StALF possessed four beta-strands and two alpha-helices. The results indicated that there were more than one ALF involved in crab immunity against various pathogens. ALFs would provide candidate promising therapeutic or prophylactic agents in health management and diseases control in crustacean aquaculture.

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

“…Comparison of their sequences with those of previously characterized ALFs showed that both contain an LPS-binding domain [33]. The sequences of PpALF2 and StALF are rich in positively charged amino acid residues: both PpALF 2 and StALF contain 12.4% lysine (Lys) and also contain 5.2% and 6.2% arginine (Arg), respectively.…”

Anti-lipopolysaccharide factor D from kuruma shrimp exhibits antiviral activity

“…ALF was first reported in chelicerates (horseshoe crab, Limulus polyphemus ) as a potent anticoagulant factor (Morita et al 1985 ; Ohashi et al 1984 ; Tanaka et al 1982 ). Since then, ALFs were identified in various crustaceans, such as portunid crabs (Afsal et al 2012 ), freshwater prawn (Ren et al 2012 ), crayfish (Jiravanichpaisal et al 2007 ; Sun et al 2011 ) and penaeid shrimp, such as Litopenaeus vannamei , Fenneropenaeus chinensis, Penaeus monodon and M . japonicus (Tassanakajon et al 2018 ).…”