title: Cleavage by signal peptide peptidase is required for the degradation of selected tail-anchored proteins.
abstract: The regulated turnover of endoplasmic reticulum (ER)-resident membrane proteins requires their extraction from the membrane lipid bilayer and subsequent proteasome-mediated degradation. Cleavage within the transmembrane domain provides an attractive mechanism to facilitate protein dislocation but has never been shown for endogenous substrates. To determine whether intramembrane proteolysis, specifically cleavage by the intramembrane-cleaving aspartyl protease signal peptide peptidase (SPP), is involved in this pathway, we generated an SPP-specific somatic cell knockout. In a stable isotope labeling by amino acids in cell culture-based proteomics screen, we identified HO-1 (heme oxygenase-1), the rate-limiting enzyme in the degradation of heme to biliverdin, as a novel SPP substrate. Intramembrane cleavage by catalytically active SPP provided the primary proteolytic step required for the extraction and subsequent proteasome-dependent degradation of HO-1, an ER-resident tail-anchored protein. SPP-mediated proteolysis was not limited to HO-1 but was required for the dislocation and degradation of additional tail-anchored ER-resident proteins. Our study identifies tail-anchored proteins as novel SPP substrates and a specific requirement for SPP-mediated intramembrane cleavage in protein turnover.
authors: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, England, UK.
authors: Jessica M
authors: JM
authors: Boname
authors: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, England, UK.
authors: Stuart
authors: S
authors: Bloor
authors: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, England, UK.
authors: Michal P
authors: MP
authors: Wandel
authors: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, England, UK.
authors: James A
authors: JA
authors: Nathan
authors: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK.
authors: Robin
authors: R
authors: Antrobus
authors: Medical Research Council National Institute for Medical Research, London NW7 1AA, England, UK.
authors: Kevin S
authors: KS
authors: Dingwell
authors: Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, England, UK.
authors: Teresa L
authors: TL
authors: Thurston
authors: Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4B, England, UK.
authors: Duncan L
authors: DL
authors: Smith
authors: Medical Research Council National Institute for Medical Research, London NW7 1AA, England, UK.
authors: James C
authors: JC
authors: Smith
authors: Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, England, UK Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, England, UK.
authors: Felix
authors: F
authors: Randow
authors: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, England, UK pjl30@cam.ac.uk.
authors: Paul J
authors: PJ
authors: Lehner
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000502:physiology*; D006367:HeLa Cells; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D040901:Proteomics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D008565:Membrane Proteins; C114025:RNF139 protein, human; D011956:Receptors, Cell Surface; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D016282:Aspartic Acid Endopeptidases; C460085:signal peptide peptidase