Capturing pore-forming intermediates of MACPF and binary toxin assemblies by cryoEM. (August 2022)

• Record Type: Journal Article
• Authors: Couves, Emma C.; Bubeck, Doryen
• Is Part Of: Current opinion in structural biology. Volume 75(2022)
• Publication Date: 2022-08
• Subjects: Molecular biology -- Periodicals; 570
• DOI: 10.1016/j.sbi.2022.102401
• Languages: English
• ISSNs: 0959-440X

Abstract

Abstract: Deployed by both pathogenic bacteria and host immune systems, pore-forming proteins rupture target membranes and can serve as conduits for effector proteins. Understanding how these proteins work relies on capturing assembly intermediates. Advances in cryoEM allowing in silico purification of heterogeneous assemblies has led to new insights into two main classes of pore-forming proteins: membrane attack complex perforin (MACPF) proteins and binary toxins. The structure of an immune activation complex, sMAC, shows how pores form by sequential templating and insertion of β-hairpins. CryoEM structures of bacterial binary toxins present a series of transitions along the pore formation pathway and reveal a general mechanism of effector protein translocation. Future developments in time-resolved cryoEM could capture and place short-lived states along the trajectory of pore-formation. Highlights: Advances in cryo EM image processing enables the capture of pore forming intermediates from both MACPF and binary toxin superfamilies. Structure of sMAC shows that pores form from sequential templating and unfurling of β-hairpins. CDT binary toxin structures explain transitions that drive pore formation. CryoEM structures of binary toxins loaded with virulence factors reveal a common mechanism of protein translocation.