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Publication Abstract from PubMed

Loading of MHC-I molecules with peptide by the catalytic chaperone tapasin in the peptide loading complex plays a critical role in antigen presentation and immune recognition. Mechanistic insight has been hampered by the lack of detailed structural information concerning tapasin-MHC-I. We present here crystal structures of human tapasin complexed with the MHC-I molecule HLA-B*44:05, and with each of two anti-tapasin antibodies. The tapasin-stabilized peptide-receptive state of HLA-B*44:05 is characterized by distortion of the peptide binding groove and destabilization of the beta(2)-microglobulin interaction, leading to release of peptide. Movements of the membrane proximal Ig-like domains of tapasin, HLA-B*44:05, and beta(2)-microglobulin accompany the transition to a peptide-receptive state. Together this ensemble of crystal structures provides insights into a distinct mechanism of tapasin-mediated peptide exchange.

Structural mechanism of tapasin-mediated MHC-I peptide loading in antigen presentation.,Jiang J, Taylor DK, Kim EJ, Boyd LF, Ahmad J, Mage MG, Truong HV, Woodward CH, Sgourakis NG, Cresswell P, Margulies DH, Natarajan K Nat Commun. 2022 Sep 17;13(1):5470. doi: 10.1038/s41467-022-33153-8. PMID:36115831^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.