Mapping the Enzyme Machineries of Cellulolytic Soil-Dwelling Bacteroidetes
Conference poster, 2019

Bacteria from the phylum Bacteroidetes are regarded as proficient degraders of complex carbohydrates, but most species are limited to soluble glycans, e.g. hemicelluloses and pectins. Two aerobic Bacteroidetes members, Cytophaga hutchinsonii and Sporocytophaga myxococcoides, have however been known as proficient cellulose metabolizers for decades, but do not conform to the known mechanisms of enzymatic cellulose conversion. Neither species encodes cellobiohydrolases or lytic polysaccharide monooxygenases, and no apparent   complexed systems such as cellulosomes have been identified.   Many Bacteroidetes species utilize so-called polysaccharide utilization loci (PULs) which encode the necessary enzymes, binding proteins, sugar transporters and regulatory elements for target polysaccharides, but also these are absent in the genomes of C. hutchinsonii and S. myxococcoides. Mutagenesis studies instead point toward the Type IX secretion system being a crucial factor in polysaccharide turnover, and it is also tightly linked to their rapid gliding motility.

In order to shed light on the enigmatic cellulolytic systems of these bacteria, we have used quantitative proteomics to map which proteins they produce during growth on cellulose and pectin, respectively, and determined the proteins’ cellular locations. Both bacteria produced similar yet distinct arrays of mostly unstudied putative cellulases during growth, and interestingly, cellulolytic activity was detected not only in the extracellular fraction and outer membrane but also intracellularly. In addition, several glycoside hydrolase family 8 (GH8) enzymes, that have previously been overlooked as potential cellulases in these species, were found to be both abundant and selectively produced during growth on cellulose. These GH8-containing proteins, which comprise large regions of unknown function and range between ~1100-2800 amino acids in total, are currently being functionally characterized to clarify their roles in cellulose turnover.

Author

Marcel Taillefer

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Andrea Seveso

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Magnus Ø. Arntzen

Norwegian University of Life Sciences

Bernard Henrissat

Aix Marseille University

Phillip B. Pope

Norwegian University of Life Sciences

Johan Larsbrink

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Wallenberg Wood Science Center Workshop
Djuronaset, Sweden,

Enzymes for selective decomposition of woody biomass

Knut and Alice Wallenberg Foundation, 2014-01-01 -- 2018-12-31.

Mapping of unstudied cellulose-degrading mechanisms in soil bacteria

Swedish Energy Agency, 2016-01-01 -- 2018-12-31.

Driving Forces

Sustainable development

Subject Categories

Biochemistry and Molecular Biology

Microbiology

Biocatalysis and Enzyme Technology

Areas of Advance

Energy

More information

Latest update

7/1/2019 1