Intrinsic folding properties of the HLA-B27 heavy chain revealed by single chain trimer versions of peptide-loaded class I Major Histocompatibility Complex molecules
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Peptide-loaded Major Histocompatibility Complex (pMHC) class I molecules can be expressed in a single chain trimeric (SCT) format, composed of a specific peptide fused to the light chain beta-2 microglobulin (β2m) and MHC class I heavy chain (HC) by flexible linker peptides. pMHC SCTs have been used as effective molecular tools to investigate cellular immunity and represent a promising vaccine platform technology, due to their intracellular folding and assembly which is apparently independent of host cell folding pathways and chaperones. However, certain MHC class I HC molecules, such as the Human Leukocyte Antigen B27 (HLA-B27) allele, present a challenge due to their tendency to form HC aggregates. We constructed a series of single chain trimeric molecules to determine the behaviour of the HLA-B27 HC in a scenario that usually allows for efficient MHC class I molecule folding. When stably expressed, a pMHC SCT incorporating HLA-B27 HC formed chaperone-bound homodimers within the endoplasmic reticulum (ER). A series of HLA-B27 SCT substitution mutations revealed that the F pocket and antigen binding groove regions of the HLA-B27 HC defined the folding and dimerisation of the single chain complex, independently of the peptide sequence. Furthermore, pMHC SCTs can demonstrate variability in their association with the intracellular antigen processing machinery.
Lenart , I , Truong , L-H , Nguyen , D D , Rasiukienė , O , Tsao , E , Armstrong , J , Kumar , P , McHugh , K , Pereira , B I , Maan , B S , Garstka , M A , Bowness , P , Blake , N , Powis , S J , Gould , K , Nesbeth , D & Antoniou , A N 2022 , ' Intrinsic folding properties of the HLA-B27 heavy chain revealed by single chain trimer versions of peptide-loaded class I Major Histocompatibility Complex molecules ' , Frontiers in Immunology , vol. 13 , 902135 . https://doi.org/10.3389/fimmu.2022.902135
Frontiers in Immunology
Copyright © 2022 Lenart, Truong, Nguyen, Rasiukienė, Tsao, Armstrong, Kumar, McHugh, Pereira, Maan, Garstka, Bowness, Blake, Powis, Gould, Nesbeth and Antoniou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
DescriptionIL was supported by Versus Arthritis studentship (17868), AA was supported by an Versus Arthritis Fellowship (15293). PK was supported by Breast Cancer Now UK (2018JulPR1086).
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