Novel family of carbohydrate-binding modules revealed by the genome sequence of spirochaeta thermophila DSM 6192

Angel Angelov, Christoph Loderer, Susanne Pompei, Wolfgang Lieb*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    13 Scopus citations

    Abstract

    Spirochaeta thermophila is a thermophilic, free-living, and cellulolytic anaerobe. The genome sequence data for this organism have revealed a high density of genes encoding enzymes from more than 30 glycoside hydrolase (GH) families and a noncellulosomal enzyme system for (hemi)cellulose degradation. Functional screening of a fosmid library whose inserts were mapped on the S. thermophila genome sequence allowed the functional annotation of numerous GH open reading frames (ORFs). Seven different GH ORFs from the S. thermophila DSM 6192 genome, all putative β-glycanase ORFs according to sequence similarity analysis, contained a highly conserved novel GH-associated module of unknown function at their C terminus. Four of these GH enzymes were experimentally verified as xylanase, β-glucanase, β-glucanase/carboxymethylcellulase (CMCase), and CMCase. Binding experiments performed with the recombinantly expressed and purified GH-associated module showed that it represents a new carbohydrate-binding module (CBM) that binds to microcrystalline cellulose and is highly specific for this substrate. In the course of this work, the new CBM type was only detected in Spirochaeta, but recently we found sequences with detectable similarity to the module in the draft genomes of Cytophaga fermentans and Mahella australiensis, both of which are phylogenetically very distant from S. thermophila and noncellulolytic, yet inhabit similar environments. This suggests a possibly broad distribution of the module in nature.

    Original languageEnglish (US)
    Pages (from-to)5483-5489
    Number of pages7
    JournalApplied and environmental microbiology
    Volume77
    Issue number15
    DOIs
    StatePublished - Aug 2011

    ASJC Scopus subject areas

    • Biotechnology
    • Food Science
    • Ecology
    • Applied Microbiology and Biotechnology

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