title: A Tunable Protein Piston That Breaks Membranes to Release Encapsulated Cargo.
abstract: Movement of molecules across membranes in response to a stimulus is a key component of cellular programming. Here, we characterize and manipulate the response of a protein-based piston capable of puncturing membranes in a pH-dependent manner. Our protein actuator consists of modified R bodies found in a bacterial endosymbiont of paramecium. We express and purify R bodies from in E. coli; these pistons undergo multiple rounds of rapid extension and retraction. We developed a high throughput screen for mutants with altered pH sensitivity for tuning of the extension process. We show that the R bodies are capable of acting as synthetic pH-dependent pistons that can puncture E. coli membranes to release the trapped content. As such, these protein machines present a novel way to selectively rupture membrane compartments and will be important for programming cellular compartmentalization.
authors.affiliation: Department of Systems Biology, Harvard Medical School , Boston, Massachusetts 02115, United States.|Wyss Institute for Biologically Inspired Engineering , Boston, Massachusetts 02115, United States.
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Polka
authors.affiliation: Department of Systems Biology, Harvard Medical School , Boston, Massachusetts 02115, United States.|Wyss Institute for Biologically Inspired Engineering , Boston, Massachusetts 02115, United States.
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Silver
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002942:Circular Dichroism; D004926:Escherichia coli / Q000378:metabolism*; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009994:Osmolar Concentration; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D016415:Sequence Alignment; D013053:Spectrophotometry
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins
keywords: Kappa particles; bioengineering; biotechnology; conformational change; protein assembly; refractile bodies