Antigenic peptide recognition on the human ABC transporter TAP resolved by DNP-enhanced solid-state NMR spectroscopy.
 

Antigenic peptide recognition on the human ABC transporter TAP resolved by DNP-enhanced solid-state NMR spectroscopy.

Related Articles Antigenic peptide recognition on the human ABC transporter TAP resolved by DNP-enhanced solid-state NMR spectroscopy.

J Am Chem Soc. 2016 Sep 23;

Authors: Lehnert E, Mao J, Mehdipour AR, Hummer G, Abele R, Glaubitz C, Tampé R

Abstract
The human transporter associated with antigen processing (TAP) is a 140-kDa heterodimeric ABC transport complex, which selects peptides for export into the endoplasmic reticulum (ER) and subsequent loading onto major histocompatibility complex class I (MHC I) molecules to trigger adaptive immune responses against virally or malignantly transformed cells. Up to date, no atomic-resolution information on the peptide-TAP interactions has been obtained, hampering the mechanistic understanding of the early steps of substrate translocation catalyzed by TAP. Here, we developed a mild method to concentrate an unstable membrane protein and combined this effort with dynamic nuclear polarization (DNP) enhanced magic angle spinning (MAS) solid-state NMR to study this challenging membrane protein-substrate complex. We were able to determine the atomic-resolution backbone conformation of an antigenic peptide bound to human TAP. Our NMR data also provide unparalleled insights into the nature of interactions between the antigen peptide side-chains and TAP. By combining NMR data and molecular modeling, the location of the peptide-binding cavity has been identified revealing a complex scenario of peptide-TAP recognition. Our findings reveal a structural and chemical basis of substrate selection rules, which define the crucial function of this ABC transporter in human immunity and health. This work is the first NMR study of a eukaryotic transporter protein and presents the power of solid-state NMR in this growing field.


PMID: 27659210 [PubMed - as supplied by publisher]



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