Genetic profiling and in silico sequence analysis of CSN2 (beta-casein) and CSN3 (κ-casein) genes in the indian buffalo (Bubalus bubalis)

Abstract

Buffalo rank second for milk production in the world and play important role in Indian economy. There are four types of caseins -S1-casein, -S2-casein, {beta}-casein and {kappa}-casein in milk. The major function of the casein protein in milk is to chelate colloidal calcium phosphate and serves as a major source of amino acids, calcium and phosphate. In buffalo milk all four casein proteins (s1, s2, {beta} and {kappa}) are encoded by four closely linked autosomal genes (CSN1S1, CSN1S2, CSN2 and CSN3 respectively) that are present on chromosome 7. Bovine CSN2 ({beta}-casein) gene is 8.5 kb long and contains nine exons and CSN3 ({kappa}-casein) is [~] 13 kb long. The aim of the study was to characterize CSN2 and CSN3 genes, In-silico analysis of {beta}-casein and {kappa}-casein protein and evolutionary relationship with other species. Buffalo mammary gland tissue was collected from local slaughterhouse (New Delhi, India) and total RNA was isolated from Buffalo Mammary Epithelial Cells. The ORF region of CSN2 and CSN3 genes were amplified and sequenced for characterization. Physiochemical properties showed that both buffalo {beta}-casein (Bu_CSN2) and {kappa}-casein (Bu_CSN3) proteins are stable and hydrophobic in nature.The presence of high phosphorylated residues in both {beta}-casein and {kappa}-casein proteins residues suggested that they are involved in signal transduction processes, cell growth and metabolism. The N-glycosylation result showed that both proteins are less in foldable state. The presence of methylation and acetylation sites in both protein revealed that they are involved in different cellular process. The evolutionary analysis showed that both buffalo genes more closely to Bos grunniens (yak).