title: A pore-forming toxin requires a specific residue for its activity in membranes with particular physicochemical properties.
abstract: The physicochemical landscape of the bilayer modulates membrane protein function. Actinoporins are a family of potent hemolytic proteins from sea anemones acting at the membrane level. This family of cytolysins preferentially binds to target membranes containing sphingomyelin, where they form lytic pores giving rise to cell death. Although the cytolytic activity of the actinoporin fragaceatoxin C (FraC) is sensitive to vesicles made of various lipid compositions, it is far from clear how this toxin adjusts its mechanism of action to a broad range of physiochemical landscapes. Herein, we show that the conserved residue Phe-16 of FraC is critical for pore formation in cholesterol-rich membranes such as those of red blood cells. The interaction of a panel of muteins of Phe-16 with model membranes composed of raft-like lipid domains is inactivated in cholesterol-rich membranes but not in cholesterol-depleted membranes. These results indicate that actinoporins recognize different membrane environments, resulting in a wider repertoire of susceptible target membranes (and preys) for sea anemones. In addition, this study has unveiled promising candidates for the development of protein-based biosensors highly sensitive to the concentration of cholesterol within the membrane.
authors.affiliation: From the Department of Bioengineering, Graduate School of Engineering and the Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa, Spain, and.
authors.forename: Koldo
authors.initials: K
authors.lastname: Morante
authors.affiliation: From the Department of Bioengineering, Graduate School of Engineering and jose@bioeng.t.u-tokyo.ac.jp.
authors.forename: Jose M M
authors.initials: JM
authors.lastname: Caaveiro
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: the Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa, Spain, and.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: González-Mañas
authors.affiliation: From the Department of Bioengineering, Graduate School of Engineering and Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan, the Medical Proteomics Laboratory, Institute of Medical Science, The University of Tokyo, Minato-ku, 108-8639 Tokyo, Japan tsumoto@bioeng.t.u-tokyo.ac.jp.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Tsumoto
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D055598:Chemical Phenomena; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D003064:Cnidarian Venoms / Q000737:chemistry* / Q000235:genetics / Q000633:toxicity*; D018360:Crystallography, X-Ray; D006461:Hemolysis / Q000187:drug effects; D008081:Liposomes; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D055550:Protein Stability; D012615:Sea Anemones / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
chemical_list: D003064:Cnidarian Venoms; D008081:Liposomes; D008563:Membrane Lipids; C545670:fragaceatoxin C; D002784:Cholesterol
keywords: Actinoporin; Cholesterol; Lipid Raft; Lipid-Protein Interaction; Membrane Structure; Pore-forming Toxin; Toxin; X-ray Crystallography