Exolysin (ExlA) from Pseudomonas aeruginosa Punctures Holes into Target Membranes Using a Molten Globule Domain

Author(s)

Bertrand, Quentin ^[1] ; Job, Viviana ^[2] ; Maillard, Antoine P. ^[2] ; Imbert, Lionel ^[1] ; Teulon, Jean-Marie ^[1] ; Favier, Adrien ^[1] ; Pellequer, Jean-Luc ^[1] ; Huber, Philippe ^[2] ; Attree, Ina ^[2] ; Dessen, Andrea ^{[1, 3]}

Affiliation

^[1] Univ Grenoble Alpes, Inst Biol Struct IBS, CEA, CNRS, F-38044 Grenoble - France

^[2] Univ Grenoble Alpes, INSERM UMR1036, CEA IRIG BCI, CNRS ERL5261, F-38000 Grenoble - France

^[3] Brazilian Biosci Natl Lab LNBio, CNPEM, BR-13084971 Campinas, SP - Brazil

• Document type: Journal article
• Source: Journal of Molecular Biology; v. 432, n. 16, p. 4466-4480, JUL 24 2020.
• Web of Science Citations: 0

Abstract

Bacteria employ several mechanisms, and most notably secretion systems, to translocate effectors from the cytoplasm to the extracellular environment or the cell surface. Pseudomonas aeruginosa widely employs secretion machineries such as the Type III Secretion System to support virulence and cytotoxicity. However, recently identified P. aeruginosa strains that do not express the Type III Secretion System have been shown to express ExlA, an exolysin translocated through a two-partner secretion system, and are the causative agents of severe lung hemorrhage. Sequence predictions of ExlA indicate filamentous hemagglutinin (FHA-2) domains as the prevalent features, followed by a C-terminal domain with no known homologs. In this work, we have addressed the mechanism employed by ExlA to target membrane bilayers by using NMR, small-angle X-ray scattering, atomic force microscopy, and cellular infection techniques. We show that the C-terminal domain of ExlA displays a ``molten globule-like{''} fold that punctures small holes into membranes composed of negatively charged lipids, while other domains could play a lesser role in target recognition. In addition, epithelial cells infected with P. aeruginosa strains expressing different ExlA variants allow localization of the toxin to lipid rafts. ExlA homologs have been identified in numerous bacterial strains, indicating that lipid bilayer destruction is an effective strategy employed by bacteria to establish interactions with multiple hosts. (C) 2020 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 17/12436-9 - ANTIBIO-BAC: exploring the bacterial cell wall as a target for novel antibiotherapies
• Grantee: Andrea Dessen de Souza e Silva
• Support Opportunities: Research Projects - SPEC Program