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Interaction pattern of Arg 62 in the A-pocket of differentially disease-associated HLA-B27 subtypes suggests distinct TCR binding modes.

Nurzia E, Narzi D, Cauli A, Mathieu A, Tedeschi V, Caristi S, Sorrentino R, Böckmann RA, Fiorillo MT - PLoS ONE (2012)

Bottom Line: Simulations of HLA:peptide systems suggest that peptide-stabilizing interactions of the Arg62 residue observed in crystal structures are metastable for both B27 subtypes under physiological conditions, rendering this arginine solvent-exposed and, probably, a key residue for TCR interaction more than peptide-binding.This view is supported by functional experiments with conservative (R62K) and non-conservative (R62A) B*2705 and B*2709 mutants that showed an overall reduction in their capability to present peptides to CD8+ T cells.Moreover, major subtype-dependent differences in the peptide recognition suggest distinct TCR binding modes for the B*2705 versus the B*2709 subtype.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Biotechnology C Darwin, Sapienza University, Rome, Italy.

ABSTRACT
The single amino acid replacement Asp116His distinguishes the two subtypes HLA-B*2705 and HLA-B*2709 which are, respectively, associated and non-associated with Ankylosing Spondylitis, an autoimmune chronic inflammatory disease. The reason for this differential association is so far poorly understood and might be related to subtype-specific HLA:peptide conformations as well as to subtype/peptide-dependent dynamical properties on the nanoscale. Here, we combine functional experiments with extensive molecular dynamics simulations to investigate the molecular dynamics and function of the conserved Arg62 of the α1-helix for both B27 subtypes in complex with the self-peptides pVIPR (RRKWRRWHL) and TIS (RRLPIFSRL), and the viral peptides pLMP2 (RRRWRRLTV) and NPflu (SRYWAIRTR). Simulations of HLA:peptide systems suggest that peptide-stabilizing interactions of the Arg62 residue observed in crystal structures are metastable for both B27 subtypes under physiological conditions, rendering this arginine solvent-exposed and, probably, a key residue for TCR interaction more than peptide-binding. This view is supported by functional experiments with conservative (R62K) and non-conservative (R62A) B*2705 and B*2709 mutants that showed an overall reduction in their capability to present peptides to CD8+ T cells. Moreover, major subtype-dependent differences in the peptide recognition suggest distinct TCR binding modes for the B*2705 versus the B*2709 subtype.

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Recognition of Npflu associated to R62K and R62A B*2705/09 mutants and wt molecules.Cytotoxic activity of a specific CTL obtained from a B*2705 positive subject (SER) against HeLa cells transfected with wt and B*2705 and B*2709 mutants and incubated with NPflu peptide (70 µM) or in medium alone and used as targets. Effector/target ratio was 15∶1. Bars represent the mean percentage of lysis ± SD of three independent experiments.
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pone-0032865-g006: Recognition of Npflu associated to R62K and R62A B*2705/09 mutants and wt molecules.Cytotoxic activity of a specific CTL obtained from a B*2705 positive subject (SER) against HeLa cells transfected with wt and B*2705 and B*2709 mutants and incubated with NPflu peptide (70 µM) or in medium alone and used as targets. Effector/target ratio was 15∶1. Bars represent the mean percentage of lysis ± SD of three independent experiments.

Mentions: The effect of Arg62 substitutions in the B27 molecules was also investigated with a peptide not having Arg at position 1. In this case, the constellation among Arg62, Glu163 and Trp167 that stabilizes peptides with pArg1 is different. To address this issue, we tested the recognition of NPflu by a specific CTL line (SER62) derived from a B*2705 positive individual. As expected, the B*2709 molecules were not able to present the peptide because of the Arg at the C-terminus (Fig. 6). In the B*2705 context, the non-conservative substitution R62A abrogated the peptide recognition while R62K mutant showed a 35% reduction of lytic activity compared to the wt molecules. This result obtained with a B27 epitope having Ser instead of Arg at P1, suggests a general relevance of Arg62 for TCR recognition of B27/peptide complexes that is only partially influenced by the amino acid specificities at P1 residue.


Interaction pattern of Arg 62 in the A-pocket of differentially disease-associated HLA-B27 subtypes suggests distinct TCR binding modes.

Nurzia E, Narzi D, Cauli A, Mathieu A, Tedeschi V, Caristi S, Sorrentino R, Böckmann RA, Fiorillo MT - PLoS ONE (2012)

Recognition of Npflu associated to R62K and R62A B*2705/09 mutants and wt molecules.Cytotoxic activity of a specific CTL obtained from a B*2705 positive subject (SER) against HeLa cells transfected with wt and B*2705 and B*2709 mutants and incubated with NPflu peptide (70 µM) or in medium alone and used as targets. Effector/target ratio was 15∶1. Bars represent the mean percentage of lysis ± SD of three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3293911&req=5

pone-0032865-g006: Recognition of Npflu associated to R62K and R62A B*2705/09 mutants and wt molecules.Cytotoxic activity of a specific CTL obtained from a B*2705 positive subject (SER) against HeLa cells transfected with wt and B*2705 and B*2709 mutants and incubated with NPflu peptide (70 µM) or in medium alone and used as targets. Effector/target ratio was 15∶1. Bars represent the mean percentage of lysis ± SD of three independent experiments.
Mentions: The effect of Arg62 substitutions in the B27 molecules was also investigated with a peptide not having Arg at position 1. In this case, the constellation among Arg62, Glu163 and Trp167 that stabilizes peptides with pArg1 is different. To address this issue, we tested the recognition of NPflu by a specific CTL line (SER62) derived from a B*2705 positive individual. As expected, the B*2709 molecules were not able to present the peptide because of the Arg at the C-terminus (Fig. 6). In the B*2705 context, the non-conservative substitution R62A abrogated the peptide recognition while R62K mutant showed a 35% reduction of lytic activity compared to the wt molecules. This result obtained with a B27 epitope having Ser instead of Arg at P1, suggests a general relevance of Arg62 for TCR recognition of B27/peptide complexes that is only partially influenced by the amino acid specificities at P1 residue.

Bottom Line: Simulations of HLA:peptide systems suggest that peptide-stabilizing interactions of the Arg62 residue observed in crystal structures are metastable for both B27 subtypes under physiological conditions, rendering this arginine solvent-exposed and, probably, a key residue for TCR interaction more than peptide-binding.This view is supported by functional experiments with conservative (R62K) and non-conservative (R62A) B*2705 and B*2709 mutants that showed an overall reduction in their capability to present peptides to CD8+ T cells.Moreover, major subtype-dependent differences in the peptide recognition suggest distinct TCR binding modes for the B*2705 versus the B*2709 subtype.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Biotechnology C Darwin, Sapienza University, Rome, Italy.

ABSTRACT
The single amino acid replacement Asp116His distinguishes the two subtypes HLA-B*2705 and HLA-B*2709 which are, respectively, associated and non-associated with Ankylosing Spondylitis, an autoimmune chronic inflammatory disease. The reason for this differential association is so far poorly understood and might be related to subtype-specific HLA:peptide conformations as well as to subtype/peptide-dependent dynamical properties on the nanoscale. Here, we combine functional experiments with extensive molecular dynamics simulations to investigate the molecular dynamics and function of the conserved Arg62 of the α1-helix for both B27 subtypes in complex with the self-peptides pVIPR (RRKWRRWHL) and TIS (RRLPIFSRL), and the viral peptides pLMP2 (RRRWRRLTV) and NPflu (SRYWAIRTR). Simulations of HLA:peptide systems suggest that peptide-stabilizing interactions of the Arg62 residue observed in crystal structures are metastable for both B27 subtypes under physiological conditions, rendering this arginine solvent-exposed and, probably, a key residue for TCR interaction more than peptide-binding. This view is supported by functional experiments with conservative (R62K) and non-conservative (R62A) B*2705 and B*2709 mutants that showed an overall reduction in their capability to present peptides to CD8+ T cells. Moreover, major subtype-dependent differences in the peptide recognition suggest distinct TCR binding modes for the B*2705 versus the B*2709 subtype.

Show MeSH
Related in: MedlinePlus