Identification of three novel myeloid cathelicidin cDNAs and their predicted peptides in buffalo (Bubalus bubalis)

Antimicrobial peptides (AMPs) are broad spectrum antibiotics, which mostly act without specific receptors. Identification of AMPs is important in the current scenario of emerging multi-drug resistant bacteria. In the present study, in an attempt to identify new AMPs, myeloid cathelicidin cDNAs were synthesized from buffalo (Bubalus bubalis) bone marrow and were amplified using specific primers. Sequence analysis of cloned cDNAs revealed three novel myeloid cathelicidins. They were named based on the number of active amino acids in the C-terminal region of their predicted peptide sequences as BuMAP-28 (having an additional Gly at position 22nd), BuMAP-29 (having an additional IIe at position 27) and BuMAP-34, compared to BMAP-27, BMAP-28 and BMAP-34 of cattle. The BuMAPs showed 93%, 95% and 87% homology respectively with that of its cattle counterpart. Predicted number of amino acids of the cDNAs was 159, 155 and 157 residues, with cationic C-terminal sequences of 28, 29 and 34, respectively, which correspond to putative antimicrobial domains. Several amino acid substitutions were observed in all the three cathelicidins. The conformation of the peptides was predicted to be alpha helical, having total net positive charge and hydrophobicity, similar to that of BMAPs in cattle. Comparative analysis of the predicted peptides suggested potential antimicrobial activity and the sequence variations detected might enable the peptides to act as effective broad spectrum antimicrobial agents.