Genetic Diversity in the N-Terminal Region of Bovine DNAJA1 Heat Shock Protein Gene in 15 Cattle Breeds from Africa, Asia and North America

DnaJ homolog, subfamily A, member 1 (Hsp40), encodes a heat shock protein which functions as a co-chaperone of the 70 kDa heat shock protein (Hsp70). As a heat shock protein gene, we hypothesize that it may be involved in heat tolerance. We investigated genetic diversity in the N- terminal region of the DNAJA1 gene in 15 cattle breeds from Africa, Asia, and North America. We amplified and sequenced a 619 base-pair fragment to reveal 25 polymorphisms in the DNAJA1 N- terminal region. No variants were observed in intron 2 but in the partial intron 3 sequence, we observed 9 polymorphisms with a deletion present in just one individual in a Pakistani breed. In-silico functional analysis with PANTHER predicted putative deleterious functional impacts of p.Gln19His, p.Ala51Val, p.Val54Met and p.Val54Glu polymorphisms. Alignment of bovine and human N-terminal J domains revealed that p.Gln19His, p. Glu20Gln, p. Glu20Ala and p. Glu20Asp missense mutations occurred in helix 2 while p. Ser49Ala, p. Ala51Val, p. Val54Met and p. Val54Glu missense mutations occurred in helix3, and both helixes have been implicated in Hsp70 binding. Twenty, two and ten haplotypes were observed in Pakistani, American and Nigerian breeds respectively suggesting that these breeds harbor genetic differences concomitant with population history and genetic diversity. Haplotype 1 was found in 36.2% of Pakistani cattle except Bhagnari; in 40% of Nigerian cattle and in 85.7% of American cattle. Our results support significant diversity at this gene locus that may have functional consequences for heat tolerance in different cattle breeds.