scholarly journals A Novel D-Galacturonate Fermentation Pathway in Lactobacillus suebicus Links Initial Reactions of the Galacturonate-Isomerase Route With the Phosphoketolase Pathway

2020 ◽  
Vol 10 ◽  
Author(s):  
Laura C. Valk ◽  
Marijke A. H. Luttik ◽  
C. de Ram ◽  
Martin Pabst ◽  
Marcel van den Broek ◽  
...  
Keyword(s):  
Phosphoketolase Pathway

scholarly journals A new insight into role of phosphoketolase pathway in Synechocystis sp. PCC 6803

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anushree Bachhar ◽  
Jiri Jablonsky
Keyword(s):  
In Silico Analysis ◽  
Bioinformatic Analysis ◽  
Phosphoglycerate Mutase ◽  
Phosphoketolase Pathway ◽  
Multi Level ◽  
Silico Analysis ◽  
Insight Into ◽  
Synechocystis Sp ◽  
Pcc 6803

AbstractPhosphoketolase (PKET) pathway is predominant in cyanobacteria (around 98%) but current opinion is that it is virtually inactive under autotrophic ambient CO2 condition (AC-auto). This creates an evolutionary paradox due to the existence of PKET pathway in obligatory photoautotrophs. We aim to answer the paradox with the aid of bioinformatic analysis along with metabolic, transcriptomic, fluxomic and mutant data integrated into a multi-level kinetic model. We discussed the problems linked to neglected isozyme, pket2 (sll0529) and inconsistencies towards the explanation of residual flux via PKET pathway in the case of silenced pket1 (slr0453) in Synechocystis sp. PCC 6803. Our in silico analysis showed: (1) 17% flux reduction via RuBisCO for Δpket1 under AC-auto, (2) 11.2–14.3% growth decrease for Δpket2 in turbulent AC-auto, and (3) flux via PKET pathway reaching up to 252% of the flux via phosphoglycerate mutase under AC-auto. All results imply that PKET pathway plays a crucial role under AC-auto by mitigating the decarboxylation occurring in OPP pathway and conversion of pyruvate to acetyl CoA linked to EMP glycolysis under the carbon scarce environment. Finally, our model predicted that PKETs have low affinity to S7P as a substrate.

scholarly journals Core Fluxome and Metafluxome of Lactic Acid Bacteria under Simulated Cocoa Pulp Fermentation Conditions

2013 ◽  
Vol 79 (18) ◽  
pp. 5670-5681 ◽  
Author(s):  
Philipp Adler ◽  
Christoph Josef Bolten ◽  
Katrin Dohnt ◽  
Carl Erik Hansen ◽  
Christoph Wittmann
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Starter Cultures ◽  
Superior Performance ◽  
Gas Chromatography Mass Spectrometry ◽  
Glycolytic Flux ◽  
Content Type ◽  
Phosphoketolase Pathway ◽  
Labeling Approach ◽  
Cocoa Fermentation

ABSTRACTIn the present work, simulated cocoa fermentation was investigated at the level of metabolic pathway fluxes (fluxome) of lactic acid bacteria (LAB), which are typically found in the microbial consortium known to convert nutrients from the cocoa pulp into organic acids. A comprehensive13C labeling approach allowed to quantify carbon fluxes during simulated cocoa fermentation by (i) parallel13C studies with [13C6]glucose, [1,2-13C2]glucose, and [13C6]fructose, respectively, (ii) gas chromatography-mass spectrometry (GC/MS) analysis of secreted acetate and lactate, (iii) stoichiometric profiling, and (iv) isotopomer modeling for flux calculation. The study of several strains ofL. fermentumandL. plantarumrevealed major differences in their fluxes. TheL. fermentumstrains channeled only a small amount (4 to 6%) of fructose into central metabolism, i.e., the phosphoketolase pathway, whereas onlyL. fermentumNCC 575 used fructose to form mannitol. In contrast,L. plantarumstrains exhibited a high glycolytic flux. All strains differed in acetate flux, which originated from fractions of citrate (25 to 80%) and corresponding amounts of glucose and fructose. Subsequent, metafluxome studies with consortia of differentL. fermentumandL. plantarumstrains indicated a dominant (96%) contribution ofL. fermentumNCC 575 to the overall flux in the microbial community, a scenario that was not observed for the other strains. This highlights the idea that individual LAB strains vary in their metabolic contribution to the overall fermentation process and opens up new routes toward streamlined starter cultures.L. fermentumNCC 575 might be one candidate due to its superior performance in flux activity.

scholarly journals Homo-d-Lactic Acid Fermentation from Arabinose by Redirection of the Phosphoketolase Pathway to the Pentose Phosphate Pathway in l-Lactate Dehydrogenase Gene-Deficient Lactobacillus plantarum

2009 ◽  
Vol 75 (15) ◽  
pp. 5175-5178 ◽  
Author(s):  
Kenji Okano ◽  
Shogo Yoshida ◽  
Tsutomu Tanaka ◽  
Chiaki Ogino ◽  
Hideki Fukuda ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactate Dehydrogenase ◽  
Lactobacillus Plantarum ◽  
Pentose Phosphate Pathway ◽  
Pentose Phosphate ◽  
Lactic Acid Fermentation ◽  
Acid Fermentation ◽  
Dehydrogenase Gene ◽  
Phosphoketolase Pathway ◽  
Optically Pure

ABSTRACT Optically pure d-lactic acid fermentation from arabinose was achieved by using the Lactobacillus plantarum NCIMB 8826 strain whose l-lactate dehydrogenase gene was deficient and whose phosphoketolase gene was substituted with a heterologous transketolase gene. After 27 h of fermentation, 38.6 g/liter of d-lactic acid was produced from 50 g/liter of arabinose.

scholarly journals Hierarchy in Pentose Sugar Metabolism in Clostridium acetobutylicum

2014 ◽  
Vol 81 (4) ◽  
pp. 1452-1462 ◽  
Author(s):  
Ludmilla Aristilde ◽  
Ian A. Lewis ◽  
Junyoung O. Park ◽  
Joshua D. Rabinowitz
Keyword(s):  
Clostridium Acetobutylicum ◽  
Sugar Metabolism ◽  
Pentose Phosphate ◽  
Acetyl Phosphate ◽  
Content Type ◽  
Acetate Excretion ◽  
Terrestrial Carbon Cycle ◽  
Pentose Sugar ◽  
Phosphoketolase Pathway ◽  
Pentose Sugars

ABSTRACTBacterial metabolism of polysaccharides from plant detritus into acids and solvents is an essential component of the terrestrial carbon cycle. Understanding the underlying metabolic pathways can also contribute to improved production of biofuels. Using a metabolomics approach involving liquid chromatography-mass spectrometry, we investigated the metabolism of mixtures of the cellulosic hexose sugar (glucose) and hemicellulosic pentose sugars (xylose and arabinose) in the anaerobic soil bacteriumClostridium acetobutylicum. Simultaneous feeding of stable isotope-labeled glucose and unlabeled xylose or arabinose revealed that, as expected, glucose was preferentially used as the carbon source. Assimilated pentose sugars accumulated in pentose phosphate pathway (PPP) intermediates with minimal flux into glycolysis. Simultaneous feeding of xylose and arabinose revealed an unexpected hierarchy among the pentose sugars, with arabinose utilized preferentially over xylose. The phosphoketolase pathway (PKP) provides an alternative route of pentose catabolism inC. acetobutylicumthat directly converts xylulose-5-phosphate into acetyl-phosphate and glyceraldehyde-3-phosphate, bypassing most of the PPP. When feeding the mixture of pentose sugars, the labeling patterns of lower glycolytic intermediates indicated more flux through the PKP than through the PPP and upper glycolysis, and this was confirmed by quantitative flux modeling. Consistent with direct acetyl-phosphate production from the PKP, growth on the pentose mixture resulted in enhanced acetate excretion. Taken collectively, these findings reveal two hierarchies in clostridial pentose metabolism: xylose is subordinate to arabinose, and the PPP is used less than the PKP.

scholarly journals Expression of the Xylulose 5-Phosphate Phosphoketolase Gene, xpkA, from Lactobacillus pentosus MD363 Is Induced by Sugars That Are Fermented via the Phosphoketolase Pathway and Is Repressed by Glucose Mediated by CcpA and the Mannose Phosphoenolpyruvate Phosphotransferase System

2002 ◽  
Vol 68 (2) ◽  
pp. 831-837 ◽  
Author(s):  
Clara C. Posthuma ◽  
Rechien Bader ◽  
Roswitha Engelmann ◽  
Pieter W. Postma ◽  
Wolfgang Hengstenberg ◽  
...  
Keyword(s):  
Protein A ◽  
Pyruvate Decarboxylase ◽  
Thiamine Pyrophosphate ◽  
Phosphotransferase System ◽  
Knockout Mutant ◽  
Lactobacillus Pentosus ◽  
Acid Protein ◽  
Phosphoketolase Pathway ◽  
Calculated Mass ◽  
Amino Acid Protein

ABSTRACT Purification of xylulose 5-phosphate phosphoketolase (XpkA), the central enzyme of the phosphoketolase pathway (PKP) in lactic acid bacteria, and cloning and sequence analysis of the encoding gene, xpkA, from Lactobacillus pentosus MD363 are described. xpkA encodes a 788-amino-acid protein with a calculated mass of 88,705 Da. Expression of xpkA in Escherichia coli led to an increase in XpkA activity, while an xpkA knockout mutant of L. pentosus lost XpkA activity and was not able to grow on energy sources that are fermented via the PKP, indicating that xpkA encodes an enzyme with phosphoketolase activity. A database search revealed that there are high levels of similarity between XpkA and a phosphoketolase from Bifidobacterium lactis and between XpkA and a (putative) protein present in a number of evolutionarily distantly related organisms (up to 54% identical residues). Expression of xpkA in L. pentosus was induced by sugars that are fermented via the PKP and was repressed by glucose mediated by carbon catabolite protein A (CcpA) and by the mannose phosphoenolpyruvate phosphotransferase system. Most of the residues involved in correct binding of the cofactor thiamine pyrophosphate (TPP) that are conserved in transketolase, pyruvate decarboxylase, and pyruvate oxidase were also conserved at a similar position in XpkA, implying that there is a similar TPP-binding fold in XpkA.

scholarly journals Metabolic Engineering of a Phosphoketolase Pathway for Pentose Catabolism in Saccharomyces cerevisiae

2004 ◽  
Vol 70 (5) ◽  
pp. 2892-2897 ◽  
Author(s):  
Marco Sonderegger ◽  
Michael Schümperli ◽  
Uwe Sauer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plant Material ◽  
Xylose Fermentation ◽  
Ethanol Yield ◽  
Limited Capacity ◽  
Fermentation Rate ◽  
Phosphoketolase Pathway ◽  
Ethanol Yields ◽  
Acetate Accumulation ◽  
Acetate Formation

ABSTRACT Low ethanol yields on xylose hamper economically viable ethanol production from hemicellulose-rich plant material with Saccharomyces cerevisiae. A major obstacle is the limited capacity of yeast for anaerobic reoxidation of NADH. Net reoxidation of NADH could potentially be achieved by channeling carbon fluxes through a recombinant phosphoketolase pathway. By heterologous expression of phosphotransacetylase and acetaldehyde dehydrogenase in combination with the native phosphoketolase, we installed a functional phosphoketolase pathway in the xylose-fermenting Saccharomyces cerevisiae strain TMB3001c. Consequently the ethanol yield was increased by 25% because less of the by-product xylitol was formed. The flux through the recombinant phosphoketolase pathway was about 30% of the optimum flux that would be required to completely eliminate xylitol and glycerol accumulation. Further overexpression of phosphoketolase, however, increased acetate accumulation and reduced the fermentation rate. By combining the phosphoketolase pathway with the ald6 mutation, which reduced acetate formation, a strain with an ethanol yield 20% higher and a xylose fermentation rate 40% higher than those of its parent was engineered.

Improved polyhydroxybutyrate production bySaccharomyces cerevisiaethrough the use of the phosphoketolase pathway

2013 ◽  
Vol 110 (8) ◽  
pp. 2216-2224 ◽  
Author(s):  
Kanokarn Kocharin ◽  
Verena Siewers ◽  
Jens Nielsen
Keyword(s):  
Phosphoketolase Pathway

Intracellular pH and the role of D-lactate dehydrogenase in the production of metabolic end products byLeuconostoc lactis

1992 ◽  
Vol 59 (3) ◽  
pp. 359-367 ◽  
Author(s):  
Richard J. Fitzgerald ◽  
Shawn Doonan ◽  
Larry L. McKay ◽  
Timothy M. Cogan
Keyword(s):  
Lactate Dehydrogenase ◽  
Intracellular Ph ◽  
Low Ph ◽  
Ph Optimum ◽  
End Products ◽  
Phosphoketolase Pathway ◽  
Intracellular Volume ◽  
Leuconostoc Lactis ◽  
Kinetics Of

SummaryThe kinetics of lactate dehydrogenase fromLeuconostoc lactisNCW1 were studied. The pH optimum for the enzyme depended on the concentration of pyruvate used in the assay and the enzyme displayed an ordered mechanism with respect to substrate binding. TheKmfor pyruvate and NADH and theVmaxof the enzyme decreased 20–, 30– and 6-fold respectively as the pH decreased from 8·0 to 5·0. No activators were found and none of the intermediates of the phosphoketolase pathway tested inhibited the enzyme. ATP, ADP, GTP and NAD+were inhibitory. The intracellular volume (Volin) and intracellular pH (pHin) decreased as the extracellular pH (pHex) decreased. Co-metabolism of citrate and glucose affected the Volinbut did not affect the pHin, which decreased by 0·6 units per unit change in pHex; at pH 7·0, the pHinand pHexwere equal. The results suggest that pHinmay play a role in determining the production of diacetyl and acetoin at low pH byLeuconostoc.

Phosphoketolase pathway contributes to carbon metabolism in cyanobacteria

Nature Plants ◽  
2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Wei Xiong ◽  
Tai-Chi Lee ◽  
Sarah Rommelfanger ◽  
Erica Gjersing ◽  
Melissa Cano ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Phosphoketolase Pathway
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