title: Phosphoketolase flux in Clostridium acetobutylicum during growth on L-arabinose.
abstract: Clostridium acetobutylicum's metabolic pathways have been studied for decades due to its metabolic diversity and industrial value, yet many details of its metabolism continue to emerge. The flux through the recently discovered pentose phosphoketolase pathway (PKP) in C. acetobutylicum has been determined for growth on xylose but transcriptional analysis indicated the pathway may have a greater contribution to arabinose metabolism. To elucidate the role of xylulose-5-phosphate/fructose-6-phosphate phosphoketolase (XFP), and the PKP in C. acetobutylicum, experimental and computational metabolic isotope analyses were performed under growth conditions of glucose or varying concentrations of xylose and arabinose. A positional bias in labelling between carbons 2 and 4 of butyrate was found and posited to be due to an enzyme isotope effect of the thiolase enzyme. A correction for the positional bias was applied, which resulted in reduction of residual error. Comparisons between model solutions with low residual error indicated flux through each of the two XFP reactions was variable, while the combined flux of the reactions remained relatively constant. PKP utilization increased with increasing xylose concentration and this trend was further pronounced during growth on arabinose. Mutation of the gene encoding XFP almost completely abolished flux through the PKP during growth on arabinose and resulted in decreased acetate/butyrate ratios. Greater flux through the PKP during growth on arabinose when compared with xylose indicated the pathway's primary role in C. acetobutylicum is arabinose metabolism.
authors.affiliation: US Army Research Laboratory, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, MD 20783, USA.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Sund
authors.affiliation: Federal Staffing Resources, 2200 Somerville Rd, Annapolis, MD 21401, USA.
authors.forename: Sanchao
authors.initials: S
authors.lastname: Liu
authors.affiliation: Oak Ridge Associated Universities, 4692 Millennium Drive, Suite 101, Belcamp, MD 21017, USA.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Germane
authors.affiliation: US Army Research Laboratory, Sensors and Electron Devices Directorate, 2800 Powder Mill Road, Adelphi, MD 20783, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Servinsky
authors.affiliation: Federal Staffing Resources, 2200 Somerville Rd, Annapolis, MD 21401, USA.
authors.forename: Elliot S
authors.initials: ES
authors.lastname: Gerlach
authors.affiliation: US Army Research Laboratory, RDRL-WML-B, 4600 Deer Creek Loop, Aberdeen Proving Ground, MD 21005, USA.
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Hurley
mesh_terms: D000446:Aldehyde-Lyases / Q000235:genetics / Q000378:metabolism*; D001089:Arabinose / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D046969:Clostridium acetobutylicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D010427:Pentose Phosphate Pathway
chemical_list: D001426:Bacterial Proteins; D001089:Arabinose; D000446:Aldehyde-Lyases; C022367:phosphoketolase; D005947:Glucose