Computational Genome-Wide Survey of some Heat Shock Protein Genes in the Bovine Genome

Genetic variability in animal response to heat stress strongly supports our ability to genetically improve thermal tolerance in domestic livestock. Heat shock protein (HSP) genes play important roles in ameliorating cellular dysfunction and maintaining protein homeostasis. We carried out a genome-wide survey and bioinformatics analysis of small HSPs (sHSP), HSP40, HSP70 and HSP90 gene families in cattle. We identified 10, 43, 10 and 4 genes belonging to sHSP, HSP40, HSP70 and HSP90 genes respectively. Members of the HSP gene family were scattered across the bovine genome, no HSP gene family was found on chromosomes 24, 26, 27 and sex chromosomes. Protein domain predictions identified a new gene, outer dense fibre of sperm tails 1 (ODF1) as a member of bovine sHSPs, showing alpha-crystalline domain conserved in all sHSPs. The J and HSP70 domains were conserved in HSP40 and HSP70 gene families while HATPase C domain was conserved in the HSP90 gene family. Evolutionary trace analysis identified residues F, P, G, P as putative evolutionary conserved residues, while exclusion of ODF-1, a distant member of sHSP family from the analysis identified additional residues of L, G, L to be evolutionarily conserved in bovine, human and mouse sHSPs.  The HPD motif in J-domains of HSP40 gene family was replaced with HPL, a motif present only in DNAJB13 gene in human, mouse and cattle. Phylogenetic results suggest predominantly monophyletic patterns, and support the need for additional functional analysis to better understand these genes in ensuring cellular homeostasis and heat tolerance in cattle.