A Pore-Forming Toxin Requires a Specific Residue for Its Activity in Membranes with Particular Physicochemical Properties

Abstract

Background: It is unclear how actinoporins adapt to the broad range of physicochemical landscapes of biological membranes. Results: A single mutation in fragaceatoxin C (an actinoporin) prevents the formation of lytic pores in membranes in the liquid-ordered phase. Conclusion: Phe-16 is critical for pore formation of fragaceatoxin C in cholesterol-rich membranes. Significance: Site-directed mutagenesis generates lipid phase-sensitive pore-forming proteins.

Cholesterol promotes Cytolysin A activity by stabilizing the intermediates during pore formation

“…This bore strong similarities to CRAC motifs that have been widely observed and characterized in many eukaryotic transmembrane proteins (42)(43)(44)(45)(46). A similar role of specific lipids in membrane partitioning of the N-terminal transmembrane helix for actinoporins, equinatoxin II, and fragaceatoxin C (FraC) has been demonstrated (47,48), suggesting conservation of membrane insertion mechanisms among the α-PFT family of proteins. In addition to stabilizing the N-terminal inserted state, MD simulations revealed that cholesterol played an important role in the ensuing stages of oligomerization by preferentially binding to a previously uncharacterized pocket formed between two adjacent β-tongues.…”

Functional characterization of Val60, a key residue involved in the membrane‐oligomerization of fragaceatoxin C, an actinoporin from Actinia fragacea

“…4A) is enthalpy-driven (DH°W T = À9.9 ± 0.5 kcal mol À1 ) and shows moderate affinity for lipids (K D WT = 16 ± 9 lM; DG°= À6.5 ± 0.3 kcal mol À1 ). The enthalpic component is partially compensated by the entropic component (ÀTDS°= 3.3 ± 0.8 kcal mol À1 ), as previously described for sticholysin II and FraC in other lipid mixtures [18,22]. In contrast, binding of V60E to liposomes generated a weak exothermic signal, nor sufficient for a reliable quantification of the thermodynamic parameters (Fig.…”

Stabilizing an amyloidogenic λ6 light chain variable domain

“…The biggest cavity in each structure depicted in purple was found in CDR1 segment and calculated with CASTp server [31]. dependent on the cell membrane environment [45]. (A) 6aJL2, (B) 6a-R25G, and (C) AR.…”

“…Check marks indicate that the respective interaction is present in the corresponding protein while dashes indicate the missing interaction. dependent on the cell membrane environment [45]. The manner in which k6 variable domain oligomers could be interacting with a specific cellular membrane might be influenced by its corresponding mutations resulting in different cellular internalization processes and phenotypic transformations [46][47][48].…”