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Lactate formation in Caldicellulosiruptor saccharolyticus is regulated by the energy carriers pyrophosphate and ATP

Willquist, Karin LU and van Niel, Ed LU (2010) In Metabolic Engineering 12. p.282-290
Abstract
Caldicellulosiruptor saccharolyticus displays superior H(2) yields on a wide range of carbon sources provided that lactate formation is avoided. Nevertheless, a low lactate flux is initiated as the growth rate declined in the transition to the stationary phase, which coincides with a drastic decrease in the glucose consumption and acetate production fluxes. In addition, the decrease in growth rate was accompanied by a sudden increase and then decrease in NADH levels. The V'(MAX) of the lactate dehydrogenase (LDH) doubled when the cells entered the stationary phase. Kinetic analysis revealed that at the metabolic level LDH activity is regulated through (i) competitive inhibition by pyrophosphate (PPi, k(i)=1.7mM) and NAD (k(i)=0.43mM) and... (More)
Caldicellulosiruptor saccharolyticus displays superior H(2) yields on a wide range of carbon sources provided that lactate formation is avoided. Nevertheless, a low lactate flux is initiated as the growth rate declined in the transition to the stationary phase, which coincides with a drastic decrease in the glucose consumption and acetate production fluxes. In addition, the decrease in growth rate was accompanied by a sudden increase and then decrease in NADH levels. The V'(MAX) of the lactate dehydrogenase (LDH) doubled when the cells entered the stationary phase. Kinetic analysis revealed that at the metabolic level LDH activity is regulated through (i) competitive inhibition by pyrophosphate (PPi, k(i)=1.7mM) and NAD (k(i)=0.43mM) and (ii) allosteric activation by FBP (300%), ATP (160%) and ADP (140%). From these data a MWC-based model was derived. Simulations with this model could explain the observed lactate shift by displaying how the sensitivity of LDH activity to NADH/NAD ratio varied with different PP(i) concentrations. Moreover, the activation of LDH by ATP indicates that C. saccharolyticus uses LDH as a means to adjusts its flux of ATP and NADH production. To our knowledge, this is the first time PPi is observed as an effector of LDH. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Metabolic Engineering
volume
12
pages
282 - 290
publisher
Elsevier
external identifiers
  • wos:000276821400010
  • pmid:20060925
  • scopus:77950864352
ISSN
1096-7176
DOI
10.1016/j.ymben.2010.01.001
language
English
LU publication?
yes
id
1f444ea0-43b8-470e-8593-38ea6eff835d (old id 1541261)
date added to LUP
2010-02-02 14:49:43
date last changed
2018-05-29 10:26:17
@article{1f444ea0-43b8-470e-8593-38ea6eff835d,
  abstract     = {Caldicellulosiruptor saccharolyticus displays superior H(2) yields on a wide range of carbon sources provided that lactate formation is avoided. Nevertheless, a low lactate flux is initiated as the growth rate declined in the transition to the stationary phase, which coincides with a drastic decrease in the glucose consumption and acetate production fluxes. In addition, the decrease in growth rate was accompanied by a sudden increase and then decrease in NADH levels. The V'(MAX) of the lactate dehydrogenase (LDH) doubled when the cells entered the stationary phase. Kinetic analysis revealed that at the metabolic level LDH activity is regulated through (i) competitive inhibition by pyrophosphate (PPi, k(i)=1.7mM) and NAD (k(i)=0.43mM) and (ii) allosteric activation by FBP (300%), ATP (160%) and ADP (140%). From these data a MWC-based model was derived. Simulations with this model could explain the observed lactate shift by displaying how the sensitivity of LDH activity to NADH/NAD ratio varied with different PP(i) concentrations. Moreover, the activation of LDH by ATP indicates that C. saccharolyticus uses LDH as a means to adjusts its flux of ATP and NADH production. To our knowledge, this is the first time PPi is observed as an effector of LDH.},
  author       = {Willquist, Karin and van Niel, Ed},
  issn         = {1096-7176},
  language     = {eng},
  pages        = {282--290},
  publisher    = {Elsevier},
  series       = {Metabolic Engineering},
  title        = {Lactate formation in Caldicellulosiruptor saccharolyticus is regulated by the energy carriers pyrophosphate and ATP},
  url          = {http://dx.doi.org/10.1016/j.ymben.2010.01.001},
  volume       = {12},
  year         = {2010},
}