title: Multiple cellobiohydrolases and cellobiose phosphorylases cooperate in the ruminal bacterium Ruminococcus albus 8 to degrade cellooligosaccharides.
abstract: Digestion of plant cell wall polysaccharides is important in energy capture in the gastrointestinal tract of many herbivorous and omnivorous mammals, including humans and ruminants. The members of the genus Ruminococcus are found in both the ruminant and human gastrointestinal tract, where they show versatility in degrading both hemicellulose and cellulose. The available genome sequence of Ruminococcus albus 8, a common inhabitant of the cow rumen, alludes to a bacterium well-endowed with genes that target degradation of various plant cell wall components. The mechanisms by which R. albus 8 employs to degrade these recalcitrant materials are, however, not clearly understood. In this report, we demonstrate that R. albus 8 elaborates multiple cellobiohydrolases with multi-modular architectures that overall enhance the catalytic activity and versatility of the enzymes. Furthermore, our analyses show that two cellobiose phosphorylases encoded by R. albus 8 can function synergistically with a cognate cellobiohydrolase and endoglucanase to completely release, from a cellulosic substrate, glucose which can then be fermented by the bacterium for production of energy and cellular building blocks. We further use transcriptomic analysis to confirm the over-expression of the biochemically characterized enzymes during growth of the bacterium on cellulosic substrates compared to cellobiose.
authors.affiliation: Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Saravanan
authors.initials: S
authors.lastname: Devendran
authors.affiliation: Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Abdel-Hamid
authors.affiliation: Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Anton F
authors.initials: AF
authors.lastname: Evans
authors.affiliation: Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Iakiviak
authors.affiliation: Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: In Hyuk
authors.initials: IH
authors.lastname: Kwon
authors.affiliation: Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Roderick I
authors.initials: RI
authors.lastname: Mackie
authors.affiliation: Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.|Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Isaac
authors.initials: I
authors.lastname: Cann
mesh_terms: D002475:Cellobiose / Q000378:metabolism*; D044602:Cellulases / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000378:metabolism*; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009844:Oligosaccharides / Q000737:chemistry; D010455:Peptides / Q000378:metabolism; D010756:Phosphoric Acids / Q000378:metabolism; D006005:Phosphorylases / Q000378:metabolism*; D011485:Protein Binding; D045857:Ruminococcus / Q000201:enzymology*; D013696:Temperature; D059467:Transcriptome
chemical_list: D009844:Oligosaccharides; D010455:Peptides; D010756:Phosphoric Acids; D002475:Cellobiose; D002482:Cellulose; C030242:phosphoric acid; D006005:Phosphorylases; D044602:Cellulases; D043366:Cellulose 1,4-beta-Cellobiosidase