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

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)5112-5122
Number of pages11
JournalEnvironmental microbiology
Volume18
Issue number12
DOIs
StatePublished - Dec 1 2016

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

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