Unknown,Transcriptomics,Genomics,Proteomics

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Expression of phosphofructokinase in Neisseria meningitidis

ABSTRACT: Neisseria meningitidis serogroup B is a pathogen that can infect diverse sites within the human host. According to the N. meningitidis genomic information and experimental observations glucose can be completely catabolized through the Entner-Doudoroff pathway and the pentose phosphate pathway. The Embden-Meyerhof-Parnas pathway is not functional, because the gene for phosphofructokinase is not present. The phylogenetic distribution of phosphofructokinase indicates that in most obligate aerobic organisms PFK is lacking. We conclude that this is because of the limited contribution of PFK to the energy supply in aerobically grown organisms in comparison with the energy generated through oxidative phosphorylation. Under anaerobic or microaerobic conditions the available energy is limiting and PFK provides an advantage, which explains the presence of PFK in many (facultative) anaerobic organisms. In accordance with this, in silico flux balance analysis predicted an increase of biomass yield as a result of PFK expression. However, analysis of a genetically engineered N. meningitidis strain that expresses a heterologous phosphofructokinase showed that the yield of biomass on substrate decreased in comparison with a pfkA deficient control strain, which was associated mainly with an increase in CO2 production, whereas production of by-products was comparable between the two strains. This might explain why the pfkA gene has not been obtained by horizontal gene transfer, since it is initially unfavourable for biomass yield. No large effects related to heterologous expression of pfkA were observed in the transcriptome. Although our results suggest that introduction of PFK does not contribute to a more efficient strain in terms of biomass yield, achievement of a robust, optimal metabolic network that enables a higher growth rate or a higher biomass yield, might be possible after adaptive evolution of the strain, which remains to be investigated. Two-condition experiment, 3 replicates per condition

ORGANISM(S): Neisseria meningitidis

SUBMITTER: Dirk Martens

PROVIDER: E-GEOD-18951 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Expression of phosphofructokinase in Neisseria meningitidis.

Baart Gino J E GJE Langenhof Marc M van de Waterbeemd Bas B Hamstra Hendrik-Jan HJ Zomer Bert B van der Pol Leo A LA Beuvery E C EC Tramper Johannes J Martens Dirk E DE

Microbiology (Reading, England) 20091001 Pt 2

Neisseria meningitidis serogroup B is a pathogen that can infect diverse sites within the human host. According to the N. meningitidis genomic information and experimental observations, glucose can be completely catabolized through the Entner-Doudoroff pathway and the pentose phosphate pathway. The Embden-Meyerhof-Parnas pathway is not functional, because the gene for phosphofructokinase (PFK) is not present. The phylogenetic distribution of PFK indicates that in most obligate aerobic organisms, ...[more]

PMID: 19797358

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Project description:Previously, it has been demonstrated that formate can be utilized by Saccharomyces cerevisiae as additional energy source using cells grown in a glucose-limited chemostat. Here, we investigated utilization of formaldehyde as co-substrate. Since endogenous formaldehyde dehydrogenase activities were insufficient to allow co-feeding of formaldehyde, the Hansenula polymorpha FLD1, encoding formaldehyde dehydrogenase, was introduced in S. cerevisiae. Chemostat cultivations revealed that formaldehyde was co-utilized with glucose, but the yield was lower than predicted. Moreover, formate was secreted by the cells. Upon co-expression of the H. polymorpha gene encoding formate dehydrogenase, FMD, the levels of secreted formate decreased, but the biomass yield was still lower than anticipated. Transcriptome comparisons of cells of the engineered FLD1/FMD-expressing S. cerevisiae strain grown with or without formaldehyde feed, suggested that the cells experienced biotin limitation, possibly due to inactivation of biotin by formaldehyde in the feed. When separate feeds were used for formaldehyde and biotin, the engineered S. cerevisiae strain was able to efficiently utilize formaldehyde as additional energy source. Experiment Overall Design: In industrial biotechnology, the cost of feedstocks (often sugars) are crucial for production of both biomass related products, such as proteins, or for the production of commodity chemicals. In many such processes a large fraction of the sugars is dissimilated to either provide free-energy (in the form of ATP) or to provide electrons (in the form of NADH). Co-consumption of methanol, which can be derived from fossil sources (via natural gas) or from biomass (via syngas) , via the above mentioned route can provide NADH and/or ATP, thereby creating the possibility to utilise the sugars more efficiently. It would therefore be advantageous to co-feed S. cerevisiae with methanol during fermentations since it is a cheap alternative to sugars as energy source. Experiment Overall Design: Efficient dissimilation of the intermediate formaldehyde is a crucial first step for utilisation of methanol by S. cerevisiae. Therefore, his study analyses the effect of co-expression of H. polymorpha FLD1 encoding NAD+-dependent formaldehyde and FMD encoding formate dehydrogenases, on tolerance to formaldehyde and co-consumption of formaldehyde by S. cerevisiae.

Dataset Information

Expression of phosphofructokinase in Neisseria meningitidis

Publications

Expression of phosphofructokinase in Neisseria meningitidis.

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