Lysozyme activity of the Ruminococcus champanellensis cellulosome

Sarah Moraïs, Darrell W Cockburn, Yonit Ben-David, Nicole M Koropatkin, Eric C Martens, Sylvia H Duncan, Harry J Flint, Itzhak Mizrahi, Edward A Bayer

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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. This article is protected by copyright.

Original languageEnglish
Pages (from-to)5112–5122
Number of pages11
JournalEnvironmental Microbiology
Issue number12
Early online date23 Aug 2016
Publication statusPublished - Dec 2016

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    Moraïs, S., Cockburn, D. W., Ben-David, Y., Koropatkin, N. M., Martens, E. C., Duncan, S. H., Flint, H. J., Mizrahi, I., & Bayer, E. A. (2016). Lysozyme activity of the Ruminococcus champanellensis cellulosome. Environmental Microbiology, 18(12), 5112–5122.