Dynamic association of the intramembrane proteases SPPL2a/b and their substrates with tetraspanin-enriched microdomains

Nadja Leinung; Torben Mentrup; Mehul Patel; Tom Gallagher; Bernd Schröder

doi:10.1016/j.isci.2023.107819

Dynamic association of the intramembrane proteases SPPL2a/b and their substrates with tetraspanin-enriched microdomains

iScience. 2023 Sep 4;26(10):107819. doi: 10.1016/j.isci.2023.107819. eCollection 2023 Oct 20.

Authors

Nadja Leinung¹, Torben Mentrup¹, Mehul Patel¹, Tom Gallagher², Bernd Schröder¹

Affiliations

¹ Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany.
² Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA.

Abstract

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.

Keywords: Biological sciences; Molecular biology; Molecular interaction.