We have described pore formation by MACPF/CDC proteins in one of the best biochemical journals. We discuss pore formation of MACPF/CDC proteins, and others, with an emphasis on formation of pores by arcs, which are unfinished rings formed at the surface of lipid membranes by pore-forming proteins.
COBISS.SI-ID: 5633562
Recent work on the MACPF/CDC superfamily of pore-forming proteins has focused on the structural analysis of monomers and pore-forming oligomeric complexes. We set the family of proteins in context and highlight aspects of their function which the direct and exclusive equation of oligomers with pores fails to explain. Starting with a description of the distribution of MACPF/CDC proteins across the domains of life, we proceed to show how their evolutionary relationships can be understood on the basis of their structural homology and re-evaluate models for pore formation by perforin, in particular. We furthermore highlight data showing the role of incomplete oligomeric rings (arcs) in pore formation and how this can explain small pores generated by oligomers of proteins belonging to the family. We set this in the context of cell biological and biophysical data on the proteins' function and discuss how this helps in the development of an understanding of how they act in processes such as apicomplexan parasites gliding through cells and exiting from cells.
COBISS.SI-ID: 5056026
From the fungus Pleurotus ostreatus, we isolated native bicomponent pore forming proteins, ostreolysin (OlyA) and pleurotolysin B (PlyB), and produced their recombinant variants, to study their lipidbinding characteristics and mechanism of poreformation in natural and artificial lipid membranes. We showed that OlyA binds selectively to membranes rich in cholesterol and sphingomyelin, but it does not permeabilize them. The recombinant, Nterminally truncated deltaPlyB with the membrane attack complexperforin (MACPF) domain, spontaneously oligomerized in solution, and bound weakly and unspecifically to lipid membranes but was not able to perforate them on its own. However, binding of deltaPlyB to the cholesterol and sphingomyelinenriched membranes, and consequently, their permeabilization was dramatically promoted in the presence of OlyA. On these membranes, deltaPlyB and OlyA formed predominantly 13meric oligomers, with outer 19.7 nm and 4.9 nm inner diameter, as imaged with electron microscopy. These oligomers representing transmembrane pores could dimerize and thus promoted aggregation of vesicles. We found that OlyA is obligatory for the deltaPlyB binding to membranes rich in cholesterol and sphingomyelin and their permeabilization. Based on the structural and functional characteristics of deltaPlyB/OlyA pores, it was shown that they are similar to MACPF proteins and bacterial cholesteroldependent cytolysins (CDC).
COBISS.SI-ID: 26868007
Sphingomyelin is an abundant lipid of cell membranes. The subcellular distribution of sphingomyelin remains unexplained. Here we examined staining of sphingomyelin in plasma membranes by two different probes, equinatoxin, a protein from sea anemones, and lysenin, a protein from earthworm. We show that plasma membrane has heterogeneous sphingomyelin pools: a pool stained by only lysenin, by EqtII, and one that is stained by both toxins. The use of the two sphingomyelin-binding probes will provide additional insights into various sphingomyelin- mediated processes in cells.
COBISS.SI-ID: 5025562
Listeriolysin O is the major factor implicated in the escape of Listeria monocytogenes from the phagolysosome. It is not understood entirely how pH specific mechanism of action is achieved by this protein. Here we studied functional and structural properties of this protein and showed that it rapidly aggregates at temperatures above 30 degrees and at neutral pH. The aggregates had the biophysical properties of amyloid. We therefore suggest that LLO spontaneously aggregates at the neutral pH found in the host cell cytosol and that this is a major mechanism of LLO inactivation.
COBISS.SI-ID: 4881690