Protein disulphide isomerase is required for signal peptide peptidase-mediated protein degradation.
The human cytomegalovirus glycoprotein US2 induces dislocation of MHC class I heavy chains from the endoplasmic reticulum (ER) into the cytosol and targets them for proteasomal degradation. Signal peptide peptidase (SPP) has been shown to be integral for US2-induced dislocation of MHC class I heavy chains although its mechanism of action remains poorly understood. Here, we show that knockdown of protein disulphide isomerase (PDI) by RNA-mediated interference inhibited the degradation of MHC class I molecules catalysed by US2 but not by its functional homolog US11. Overexpression of the substrate-binding mutant of PDI, but not the catalytically inactive mutant, dominant-negatively inhibited US2-mediated dislocation of MHC class I molecules by preventing their release from US2. Furthermore, PDI associated with SPP independently of US2 and knockdown of PDI inhibited SPP-mediated degradation of CD3delta but not Derlin-1-dependent degradation of CFTR DeltaF508. Together, our data suggest that PDI is a component of the SPP-mediated ER-associated degradation machinery.
Lee
Seong-Ok
SO
Department of Biological Sciences, National Creative Research Center for Antigen Presentation, Seoul National University, Seoul, South Korea.
Cho
Kwangmin
K
Cho
Sunglim
S
Kim
Ilkwon
I
Oh
Changhoon
C
Ahn
Kwangseog
K
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D003587:Cytomegalovirus / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006367:HeLa Cells; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D034622:RNA Interference; D016601:RNA-Binding Proteins / Q000378:metabolism; D013379:Substrate Specificity; D014759:Viral Envelope Proteins / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism
C487709:DERL1 protein, human; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D016601:RNA-Binding Proteins; C074546:US11 protein, herpesvirus; C118670:US2 protein, Varicellovirus; D014759:Viral Envelope Proteins; D014764:Viral Proteins; D016282:Aspartic Acid Endopeptidases; C460085:signal peptide peptidase; D019704:Protein Disulfide-Isomerases