A phylogenetic analysis of cattle DRB3 alleles with a deletion of codon 65.
One of the most common cattle major histocompatibility complex DRB3 alleles, *0201, includes a deletion of codon 65 encoding one residue in the alpha-helical chain. The mutation is functionally interesting and is likely to influence peptide binding. Exon 2 of two additional del65 alleles, *3301 and *4101, have now been sequenced with the aim to investigate the evolutionary relationship of this allelic group. Despite a fairly large genetic distance between the three alleles (11-17 nucleotide substitutions causing 8-11 amino acid substitutions) we found clear indications of a common ancestry. The alpha-helical region was very similar or identical among the alleles whereas the beta-strand region was quite divergent. The results indicated that interallelic recombination has contributed to the diversification of the del65 group. Deletion of codon 65 has also been found in a roe deer DRB1 allele and a cattle DQB3 allele. Sequence comparisons of the cattle and roe deer DRB del65 alleles refuted the possibility of a trans-species persistence of a del65 allelic lineage but the two species may share a short ancestral sequence motif including del65. In addition to del65, the cattle DQB3 allele did not show any striking sequence similarities to the DRB alleles.
Mikko
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Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 597, S-751 24 Uppsala, Sweden.
Lewin
H A
HA
Andersson
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L
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003062:Codon; D003670:Deer / Q000235:genetics / Q000276:immunology; D017353:Gene Deletion; D006649:Histocompatibility Antigens / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017386:Sequence Homology, Amino Acid
D003062:Codon; D006649:Histocompatibility Antigens