title: Putting life on ice: bacteria that bind to frozen water.
abstract: Ice-binding proteins (IBPs) are typically small, soluble proteins produced by cold-adapted organisms to help them avoid ice damage by either resisting or tolerating freezing. By contrast, the IBP of the Antarctic bacterium Marinomonas primoryensis is an extremely long, 1.5 MDa protein consisting of five different regions. The fourth region, a 34 kDa domain, is the only part that confers ice binding. Bioinformatic studies suggest that this IBP serves as an adhesin that attaches the bacteria to ice to keep it near the top of the water column, where oxygen and nutrients are available. Using temperature-controlled cells and a microfluidic apparatus, we show that M. primoryensis adheres to ice and is only released when melting occurs. Binding is dependent on the mobility of the bacterium and the functionality of the IBP domain. A polyclonal antibody raised against the IBP region blocks bacterial ice adhesion. This concept may be the basis for blocking biofilm formation in other bacteria, including pathogens. Currently, this IBP is the only known example of an adhesin that has evolved to bind ice.
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
authors.forename: Maya
authors.identifier: 0000-0001-8619-8481
authors.initials: M
authors.lastname: Bar Dolev
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
authors.forename: Reut
authors.initials: R
authors.lastname: Bernheim
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6.
authors.forename: Shuaiqi
authors.initials: S
authors.lastname: Guo
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6.
authors.forename: Peter L
authors.initials: PL
authors.lastname: Davies
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel ido.braslavsky@mail.huji.ac.il.
authors.forename: Ido
authors.initials: I
authors.lastname: Braslavsky
mesh_terms: D000864:Antarctic Regions; D001422:Bacterial Adhesion / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D007053:Ice; D053544:Marinomonas / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D007053:Ice
keywords: RTX adhesin; antifreeze proteins; biofilm; cold adaptation; ice-binding proteins; microfluidic cold finger