Department / Course College of Life Sciences Department of Biotechnology
Title / Position Assistant Professor
Language English
Publication Date 2012/12
Type Research paper (scientific journal)
Peer Review Yes
Title Enzymatic Characterization of AMP Phosphorylase and Ribose-1,5-Bisphosphate Isomerase Functioning in an Archaeal AMP Metabolic Pathway
Volume, Issue, Page 194(24),6847-6855
Author and coauthor Riku Aono,Takaaki Sato,Ayumu Yano,Shosuke Yoshida,Yuichi Nishitani,Kunio Miki,Tadayuki Imanaka,Haruyuki Atomi
Details 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 alpha-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.
DOI 10.1128/JB.01335-12
ISSN 00219193
PMID 23065974