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Title: Enzymatic characterization of AMP phosphorylase and ribose-1,5-bisphosphate isomerase functioning in an archaeal AMP metabolic pathway.
Authors: Aono, Riku
Sato, Takaaki
Yano, Ayumu
Yoshida, Shosuke  kyouindb  KAKEN_id
Nishitani, Yuichi
Miki, Kunio  kyouindb  KAKEN_id
Imanaka, Tadayuki
Atomi, Haruyuki  kyouindb  KAKEN_id  orcid (unconfirmed)
Author's alias: 佐藤, 喬章
跡見, 晴幸
Issue Date: Dec-2012
Publisher: American Society for Microbiology
Journal title: Journal of bacteriology
Volume: 194
Issue: 24
Start page: 6847
End page: 6855
Abstract: AMP phosphorylase (AMPpase), ribose-1, 5-bisphosphate (R15P) isomerase, and type III ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) have been proposed to constitute a novel pathway involved in AMP metabolism in the Archaea. Here we performed a biochemical examination of AMPpase and R15P isomerase from Thermococcus kodakarensis. R15P isomerase was specific for the α-anomer of R15P and did not recognize other sugar compounds. We observed that activity was extremely low with the substrate R15P alone but was dramatically activated in the presence of AMP. Using AMP-activated R15P isomerase, we reevaluated the substrate specificity of AMPpase. AMPpase exhibited phosphorylase activity toward CMP and UMP in addition to AMP. The [S]-v plot (plot of velocity versus substrate concentration) of the enzyme toward AMP was sigmoidal, with an increase in activity observed at concentrations higher than approximately 3 mM. The behavior of the two enzymes toward AMP indicates that the pathway is intrinsically designed to prevent excess degradation of intracellular AMP. We further examined the formation of 3-phosphoglycerate from AMP, CMP, and UMP in T. kodakarensis cell extracts. 3-Phosphoglycerate generation was observed from AMP alone, and from CMP or UMP in the presence of dAMP, which also activates R15P isomerase. 3-Phosphoglycerate was not formed when 2-carboxyarabinitol 1, 5-bisphosphate, a Rubisco inhibitor, was added. The results strongly suggest that these enzymes are actually involved in the conversion of nucleoside monophosphates to 3-phosphoglycerate in T. kodakarensis.
Rights: © 2012, American Society for Microbiology.
This is not the published version. Please cite only the published version.
DOI(Published Version): 10.1128/JB.01335-12
PubMed ID: 23065974
Appears in Collections:Journal Articles

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