Distinct functions for the glycans of tapasin and heavy chains in the assembly of MHC class I molecules.
Complexes of specific assembly factors and generic endoplasmic reticulum (ER) chaperones, collectively called the MHC class I peptide-loading complex (PLC), function in the folding and assembly of MHC class I molecules. The glycan-binding chaperone calreticulin (CRT) and partner oxidoreductase ERp57 are important in MHC class I assembly, but the sequence of assembly events and specific interactions involved remain incompletely understood. We show that the recruitments of CRT and ERp57 to the PLC are codependent and also dependent upon the ERp57 binding site and the glycan of the assembly factor tapasin. Furthermore, the ERp57 binding site and the glycan of tapasin enhance β(2)m and MHC class I heavy (H) chain recruitment to the PLC, with the ERp57 binding site having the dominant effect. In contrast, the conserved MHC class I H chain glycan played a minor role in CRT recruitment into the PLC, but impacted the recruitment of H chains into the PLC, and glycan-deficient H chains were impaired for tapasin-independent and tapasin-assisted assembly. The conserved MHC class I glycan and tapasin facilitated an early step in the assembly of H chain-β(2)m heterodimers, for which tapasin-ERp57 or tapasin-CRT complexes were not required. Together, these studies provide insights into how PLCs are constructed, demonstrate two distinct mechanisms by which PLCs can be stabilized, and suggest the presence of intermediate H chain-deficient PLCs.
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Syed Monem
SM
Rizvi
Natasha
N
Del Cid
Lonnie
L
Lybarger
Malini
M
Raghavan
D019943:Amino Acid Substitution / Q000235:genetics / Q000276:immunology; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D017124:Conserved Sequence / Q000276:immunology; D015789:HLA-A2 Antigen / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D017510:Protein Folding; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D001613:beta 2-Microglobulin / Q000172:deficiency / Q000235:genetics
D015789:HLA-A2 Antigen; D026901:Membrane Transport Proteins; D010446:Peptide Fragments; D011134:Polysaccharides; D001613:beta 2-Microglobulin; C107762:tapasin
FASEB J. 2001 Jun;15(8):1448-50
11387253
Eur J Immunol. 2009 Sep;39(9):2371-6
19701894
Proc Natl Acad Sci U S A. 2006 Nov 28;103(48):18220-5
17116884
J Biol Chem. 2010 Feb 12;285(7):4520-35
19959473
Tissue Antigens. 2003 Nov;62(5):385-93
14617045
Immunity. 2009 Jan 16;30(1):21-32
19119025
Nature. 1994 Apr 28;368(6474):864-7
8159247
J Immunol. 1989 May 1;142(9):3320-8
2785140
J Immunol. 1986 Oct 1;137(7):2299-306
3760563
Immunology. 2008 May;124(1):112-20
18194274
J Cell Biol. 2004 Dec 6;167(5):903-13
15569716
Immunity. 2002 Jan;16(1):99-109
11825569
J Biol Chem. 2004 Jun 11;279(24):25112-21
15056662
Eur J Immunol. 1999 Jun;29(6):1858-70
10382748
Scand J Immunol. 1994 Jan;39(1):64-72
8290894
J Biol Chem. 1995 Feb 24;270(8):3944-8
7876141
Eur J Immunol. 2003 Jan;33(1):264-73
12594855
Traffic. 2010 Mar;11(3):332-47
20070606
Mol Biol Cell. 2008 Jun;19(6):2413-23
18337472
J Biol Chem. 2008 Jun 13;283(24):16469-76
18420581
J Immunol. 1995 Jul 1;155(1):143-8
7602092
J Immunol. 1998 Jun 1;160(11):5404-9
9605141
Int Immunol. 2001 Oct;13(10):1275-82
11581172
Immunity. 2002 Jan;16(1):87-98
11825568
EMBO J. 2005 Oct 19;24(20):3613-23
16193070
J Immunol. 1997 Mar 1;158(5):2236-41
9036970
Proc Natl Acad Sci U S A. 1988 Jan;85(1):227-31
3257565
Mol Cell. 2001 Sep;8(3):633-44
11583625
J Biol Chem. 2002 Nov 29;277(48):46415-23
12235131
Curr Opin Cell Biol. 2008 Dec;20(6):624-31
18926908
Immunol Cell Biol. 2010 Jan;88(1):57-62
19687800
Proc Natl Acad Sci U S A. 2008 Jul 29;105(30):10477-82
18650385
Nat Immunol. 2007 Aug;8(8):864-72
17603488
J Immunol. 2001 Feb 1;166(3):1703-9
11160214
Cold Spring Harb Symp Quant Biol. 1995;60:267-75
8824400
Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):1954-9
11842220
Annu Rev Biochem. 2004;73:1019-49
15189166
Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12716-20
7809108
Immunity. 1996 Aug;5(2):103-14
8769474
J Immunol. 1995 Nov 15;155(10):4726-33
7594473
Immunity. 1998 Feb;8(2):221-31
9492003
Science. 1994 May 27;264(5163):1322-6
8191286
Eur J Immunol. 1979 Jul;9(7):536-45
91522
Proc Natl Acad Sci U S A. 1993 Sep 15;90(18):8392-6
7690960