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1: EMBO J. 2007 Mar 21;26(6):1681-90. Epub 2007 Mar 1.
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Analysis of interactions in a tapasin/class I complex provides a mechanism for peptide selection.

Chen M, Bouvier M.

School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA.

We examined interactions in a soluble tapasin (TPN)/HLA-B*0801 complex to gain mechanistic insights into the functions of TPN. Results show that TPN acts as a chaperone by increasing the ratio of active-to-inactive peptide-deficient HLA-B*0801 molecules in solution. TPN causes peptides to associate and dissociate faster owing to its effect on widening the binding groove of HLA-B*0801 molecules. Our data indicate that a TPN-assisted mechanism of peptide selection relies on disruption of conserved hydrogen bonds at the C-terminal end of the groove. Peptide sequence-dependent interactions along the entire length of the groove also play a role in this mechanism. We suggest that TPN influences presentation of antigenic peptides according to a mechanistically complicated process in which bound candidate peptides that are unable to conformationally disengage TPN from class I molecules are excluded from the repertoire. Overall, these studies unify our understanding of the functions of TPN.

Publication Types:
PMID: 17332746 [PubMed - indexed for MEDLINE]

PMCID: PMC1829385