Not sorcery after all: Roles of multiple charged residues in membrane insertion of gasdermin-A3

Abstract

Gasdermins execute programmatory cell death, known as pyroptosis, by forming medium-sized membrane pores. Recently, the molecular structure of those pores as well as the diversity in their shape and size have been revealed by cryoTEM and atomic force microscopy, respectively. Even though a growth of smaller to larger oligomers and reshaping from slits to rings could be documented, the initiation of the gasdermin pore formation remains a mystery. In one hypothesis, gasdermin monomers insert into membranes before associating into oligomeric pores. In the other hypothesis, gasdermin oligomers preassemble on the membrane surface prior to membrane insertion. Here, by studying the behavior of monomeric membrane-inserted gasdermin-A3 (GSDMA3), we unveil that a monomeric gasdermin prefers the membrane-adsorbed over the membrane-inserted state. Our results thus support the hypothesis of oligomers preassembling on the membrane surface before membrane penetration. At the same time, our simulations of small membrane-inserted arcs of GSDMA3 suggest that the inserting oligomer can be small and does not have to comprise a full ring of approximately 26–30 subunits. Moreover, our simulations have revealed an astonishingly large impact of salt-bridge formation and protein surroundings on the transmembrane passage of charged residues, reducing the energetic cost by up to 53% as compared to their free forms. The here observed free energy barrier of mere 5.6 kcal/mol for the membrane insertion of monomeric GSDMA3 explains the surprising ability of gasdermins to spontaneously self-insert into cellular membranes.

Structural basis of NINJ1-mediated plasma membrane rupture in cell death

“…In all-atom simulations CHARMM36m 65 , 66 was used in combination with the TIP4p water model 67 . Details on simulation setup parameters can be found in our recent publication 68 . In case of ‘endless’ linear polymers, the compressibility of the box along the polymer was set to 4.5 × 10 −7 bar −1 .…”

BCL-2 and BOK regulate apoptosis by interaction of their C-terminal transmembrane domains

“…This asymmetric interaction interface appeared stable over the course of atomistic simulations, indicating its specificity. The strong tilt of the peptides in the bilayer and their shift relative to each other enable the charged residues K202, R199, of individual BOK peptides to snorkel to the lipid headgroups of different membrane leaflets (Rabe et al 2016; Korn und Pluhackova 2022) (Figure S5).…”

Precise Orchestration of Gasdermins' Pore-Forming Function by Posttranslational Modifications in Health and Disease

“…GSDMs-mediated pore formation is dynamically regulated at multiple levels through autoinhibitory structures, proteolytic cleavage, lipid binding and membrane translocation (oligomerization and pre-pore formation), oligomerization (pore formation) and pore removal for membrane repair [40,[43][44][45][46][47][48][49][50][51] (Figure 2A). Under normal circumstances, most GSDMs are located in the cytoplasm in an autoinhibited conformation [44].…”