title: The Cytosolic Oligosaccharide-Degrading Proteome of Butyrivibrio Proteoclasticus.
abstract: The growth and productivity of ruminants depends on a complex microbial community found in their fore-stomach (rumen), which is able to breakdown plant polysaccharides and ferment the released sugars. Butyrivibrio proteoclasticus B316T is a Gram-positive polysaccharide-degrading, butyrate-producing bacterium that is present at high numbers in the rumen of animals consuming pasture or grass silage based diets. B316T is one of a small number of rumen fibrolytic microbes capable of efficiently degrading and utilizing xylan, as well as being capable of utilizing arabinose, xylose, pectin and starch. We have therefore carried out a proteomic analysis of B316T to identify intracellular enzymes that are implicated in the metabolism of internalized xylan. Three hundred and ninety four proteins were identified including enzymes that have potential to metabolize assimilated products of extracellular xylan digestion. Identified enzymes included arabinosidases, esterases, an endoxylanase, and β-xylosidase. The presence of intracellular debranching enzymes indicated that some hemicellulosic side-chains may not be removed until oligosaccharides liberated by extracellular digestion have been assimilated by the cells. The results support a model of extracellular digestion of hemicellulose to oligosaccharides that are then transported to the cytoplasm for further digestion by intracellular enzymes.
authors.affiliation: Rumen Microbiology, Animal Science Group, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand. jonathan.dunne@gmri.org.nz.|Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. jonathan.dunne@gmri.org.nz.|AgResearch Limited/Victoria University of Wellington Proteomics Laboratory, Victoria University of Wellington, Wellington 6140, New Zealand. jonathan.dunne@gmri.org.nz.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Dunne
authors.affiliation: Rumen Microbiology, Animal Science Group, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand. bill.kelly@agresearch.co.nz.
authors.forename: William J
authors.initials: WJ
authors.lastname: Kelly
authors.affiliation: Rumen Microbiology, Animal Science Group, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand. sinead.leahy@agresearch.co.nz.
authors.forename: Sinead C
authors.initials: SC
authors.lastname: Leahy
authors.affiliation: Rumen Microbiology, Animal Science Group, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand. dong.li@agresearch.co.nz.
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.affiliation: Rumen Microbiology, Animal Science Group, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand. jude.bond@dpi.nsw.gov.au.|Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. jude.bond@dpi.nsw.gov.au.|AgResearch Limited/Victoria University of Wellington Proteomics Laboratory, Victoria University of Wellington, Wellington 6140, New Zealand. jude.bond@dpi.nsw.gov.au.
authors.forename: Judy J
authors.initials: JJ
authors.lastname: Bond
authors.affiliation: Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. lifeng.peng@vuw.ac.nz.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Peng
authors.affiliation: Rumen Microbiology, Animal Science Group, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand. graeme.attwood@agresearch.co.nz.
authors.forename: Graeme T
authors.initials: GT
authors.lastname: Attwood
authors.affiliation: Centre for Biodiscovery and School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand. bill.jordan@vuw.ac.nz.
authors.forename: T William
authors.initials: TW
authors.lastname: Jordan
keywords: butyrivibrio proteoclasticus; carbohydrate active enzymes; hemicellulose; oligosaccharidases; proteomics; rumen; xylan