title: Membrane Curvature Affects the Formation of α-Hemolysin Nanopores.
abstract: Membrane proteins perform their functions within or on the lipid membrane, and lipid compositions are known to affect membrane protein integration and activity. Recently, the geometric aspect of membrane curvature was shown to play an important role in membrane protein behavior. Certain membrane proteins are known to sense the curvature of the membrane and to preferentially bind to highly curved membranes. However, although numerous membrane proteins assemble to form homo- or heterocomplexes and perform their biological functions, the dependence of membrane protein assembly on membrane curvature remains elusive. In this study, we analyzed the effect of the membrane curvature on the nanopore formation of α-hemolysin (AH), which is a toxic membrane protein derived from Staphylococcus aureus. The AH protein binds to the membrane as a monomer, assembles to form a heptamer, and forms a nanopore. By simultaneously measuring the molecules bound to the membrane and the activities of the nanopore on the membrane, we determined the nanopore formation ratio of AH. We used various sizes of liposomes and analyzed the dependence on the membrane curvature by using flow cytometry. Combining the results for positive and negative curvature, we found that the nanopore formation ratio of AH was curvature sensitive and was higher in a flat membrane than in a curved membrane. Furthermore, the nanopore formation ratio was almost identical or relatively higher in membranes with negative curvature than those with positive curvature.
authors: †Japan Science and Technology (JST), ERATO, Yomo Dynamical Micro-scale Reaction Environment Project, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Satoshi
authors: S
authors: Fujii
authors: †Japan Science and Technology (JST), ERATO, Yomo Dynamical Micro-scale Reaction Environment Project, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.|‡Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Tomoaki
authors: T
authors: Matsuura
authors: †Japan Science and Technology (JST), ERATO, Yomo Dynamical Micro-scale Reaction Environment Project, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.|§Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.|∥Graduate School of Frontier Biosciences, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.|⊥Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, 152-8550, Japan.
authors: Tetsuya
authors: T
authors: Yomo
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000378:metabolism; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D058608:Nanopores / Q000648:ultrastructure; D011485:Protein Binding; D055503:Protein Multimerization; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism
chemical_list: D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D008081:Liposomes; C021091:staphylococcal alpha-toxin