Molecular characterization and in-silico analysis of complete coding sequence of bubaline mLYS

Abstract

The role of immune-relevant genes involved in disease biology as well as innate and adaptive immunity is at the centre stage while exploring the genetic basis of disease occurrence. The macrophage expressed lysozyme gene product contributes to innate immunity by cleaving the ß- 1,4 linkage of bacterial peptidoglycan in phagocytosis. Higher specific activity observed in bubaline milk/ serum lysozymes over their bovine counterparts is expected to contribute higher resistances to diseases in general and mastitis in particular. To explore the reasons for higher activity in terms of sequence variations, macrophage expressed lysozyme cDNA was synthesized, cloned and sequenced. The 593 bp mRNA sequence revealed a 444 bp (27nt to 470nt) ORF bearing usual start codon ATG and end codon TAA with GC content of 46 % coding for precursor polypeptide of 147 amino acids. The comparative sequence analysis of cattle and buffalo revealed the difference at 10 places leading to 3 non-synonymous (5th, 116th and 142th) substitutions which did not affect the predicted 3D structure. The mLYS polypeptide had signal sequence (1st to 18th residue) and the mature peptide had two lysozyme catalytic sites, three Ca++ binding sites as well as eleven catalytic clefts prominent among the conserved domains. Secondly, bubaline mLYS was phylogenetically closer to the abomasum type than mammary gland type. The high similarity in the coding sequences and predicted structure suggested that bubaline lysozyme gene if hyper-expressed either in native or recombinant form in bovine udder may result in better udder health.