Signal peptide peptidase-like 2a and b (SPPL2a/b) are aspartyl intramembrane proteases and cleave tail-anchored proteins as well as N-terminal fragments (NTFs) derived from type II-oriented transmembrane proteins. How these proteases recruit substrates and cleavage is regulated, is still incompletely understood. We found that SPPL2a/b localize to detergent-resistant membrane (DRM) domains with the characteristics of tetraspanin-enriched microdomains (TEMs). Based on this, association with several tetraspanins was evaluated. We demonstrate that not only SPPL2a/b but also their substrates tumor necrosis factor (TNF) and CD74 associate with tetraspanins like CD9, CD81, and CD82 and/or TEMs and analyze the stability of these complexes in different detergents. CD9 and CD81 deficiency has protease- and substrate-selective effects on SPPL2a/b function. Our findings suggest that reciprocal interactions with tetraspanins may assist protease-substrate encounters of SPPL2a/b within the membrane. Beyond SPP/SPPL proteases, this supports previous concepts that tetraspanins facilitate membrane-embedded proteolytic processes.
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http://dx.doi.org/10.1016/j.isci.2023.107819 | DOI Listing |
Food Chem
December 2024
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830017, China. Electronic address:
ACS Med Chem Lett
December 2024
Laboratory of Chemical Biology, Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Herestraat 49 box 901b, 3000 Leuven, Belgium.
Rhomboid proteases play a variety of physiological roles, but rhomboid protease inhibitors have been mostly developed for the model rhomboid GlpG. In this work, we screened different electrophilic scaffolds against the human mitochondrial rhomboid PARL and found 4-oxo-β-lactams as submicromolar inhibitors. Multifaceted computations suggest explanations for the activity at the molecular scale and provide models of covalently bound complexes.
View Article and Find Full Text PDFFront Aging Neurosci
November 2024
Science and Experimental Research Center of Shenyang Medical College, Shenyang, Liaoning, China.
Biochem Biophys Res Commun
December 2024
College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin 300071, China; Tianjin Key Laboratory of Protein Science, Nankai University, Tianjin 300071, China. Electronic address:
Regulated intramembrane proteolysis (RIP) is a fundamentally conserved mechanism involving sequential cleavage by a membrane-bound Site-1 protease (S1P) and a transmembrane Site-2 protease (S2P). In the opportunistic pathogen Pseudomonas aeruginosa, the alternate sigma factor σ activates alginate production and in turn is regulated by the MucABCD system. The anti-sigma factor MucA, which inhibits σ, is sequentially cleaved via RIP by AlgW (S1P) and MucP (S2P) respectively.
View Article and Find Full Text PDFJ Cell Sci
December 2024
Sir William Dunn School of Pathology , University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
Cleavage of transmembrane segments on target proteins by the aspartyl intramembrane protease signal peptide peptidase (SPP, encoded by HM13) has been linked to immunity, viral infection and protein quality control. How SPP recognizes its various substrates and specifies their fate remains elusive. Here, we identify the lanosterol demethylase CYP51A1 as an SPP substrate and show that SPP-catalysed cleavage triggers CYP51A1 clearance by endoplasmic reticulum-associated degradation (ERAD).
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