title: Lysozyme activity of the Ruminococcus champanellensis cellulosome.
abstract: Ruminococcus champanellensis is a keystone species in the human gut that produces an intricate cellulosome system of various architectures. A variety of cellulosomal enzymes have been identified, which exhibit a range of hydrolytic activities on lignocellulosic substrates. We describe herein a unique R. champanellensis scaffoldin, ScaK, which is expressed during growth on cellobiose and comprises a cohesin module and a family 25 glycoside hydrolase (GH25). The GH25 is non-autolytic and exhibits lysozyme-mediated lytic activity against several bacterial species. Despite the narrow acidic pH curve, the enzyme is active along a temperature range from 2 to 85°C and is stable at very high temperatures for extended incubation periods. The ScaK cohesin was shown to bind selectively to the dockerin of a monovalent scaffoldin (ScaG), thus enabling formation of a cell-free cellulosome, whereby ScaG interacts with a divalent scaffodin (ScaA) that bears the enzymes either directly or through additional monovalent scaffoldins (ScaC and ScaD). The ScaK cohesin also interacts with the dockerin of a protein comprising multiple Fn3 domains that can potentially promote adhesion to carbohydrates and the bacterial cell surface. A cell-free cellulosomal GH25 lysozyme may provide a bacterial strategy to both hydrolyze lignocellulose and repel eventual food competitors and/or cheaters.
authors.affiliation: Biomolecular Sciences Department, The Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Sarah
authors.initials: S
authors.lastname: Moraïs
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
authors.forename: Darrell W
authors.initials: DW
authors.lastname: Cockburn
authors.affiliation: Biomolecular Sciences Department, The Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Yonit
authors.initials: Y
authors.lastname: Ben-David
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Koropatkin
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Martens
authors.affiliation: Microbiology Group, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
authors.forename: Sylvia H
authors.initials: SH
authors.lastname: Duncan
authors.affiliation: Microbiology Group, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Flint
authors.affiliation: The Department of Life Sciences & the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
authors.forename: Itzhak
authors.initials: I
authors.lastname: Mizrahi
authors.affiliation: Biomolecular Sciences Department, The Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Bayer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D044603:Cellulosomes / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009113:Muramidase / Q000235:genetics / Q000378:metabolism*; D045857:Ruminococcus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002482:Cellulose; D009113:Muramidase