Structural analysis of H-2Kf and H-2Kfm1 by using H-2K locus-specific sequences

Area of Science:

• Immunogenetics
• Molecular Biology
• Protein Chemistry

Background:

• The H-2Kf allele and its spontaneous mutant, Kfm1, are crucial for understanding immune responses.
• Investigating mutations within the H-2K locus provides insights into major histocompatibility complex (MHC) function.

Purpose of the Study:

• To clone and characterize the H-2Kf allele and the Kfm1 mutant.
• To elucidate the structural and genetic implications of the observed mutations.
• To explore the impact of these mutations on allogeneic properties and serologic phenotype.

Main Methods:

• Locus-specific sequencing was employed to clone the H-2Kf allele and the Kfm1 mutant.
• Analysis of nucleotide and amino acid sequences to identify specific changes.
• Assessment of binding affinities to alloantisera and monoclonal antibodies (mAb).

Main Results:

• The Kfm1 mutation involves four nucleotide changes, leading to amino acid substitutions at positions 95 and 97 within the antigen recognition site.
• These substitutions influence allogeneic properties, supporting the peptide presentation hypothesis of alloreactivity.
• The mutant exhibits reduced binding to anti-Kf alloantisera and mAb, indicating indirect effects on serologic phenotype.
• The mutated region's sequence homology to the Df gene suggests a gene conversion-like mechanism in the H-2f haplotype.

Conclusions:

• The identified mutations provide structural and genetic insights into MHC class I function.
• The findings support the role of altered peptide presentation in T cell alloreactivity.
• A gene conversion-like mechanism is implicated in H-2f haplotype evolution.
• The cloning strategy offers a valuable method for isolating other MHC alleles.