scholarly journals The Transcription Factor StuA Regulates Central Carbon Metabolism, Mycotoxin Production, and Effector Gene Expression in the Wheat Pathogen Stagonospora nodorum

2010 ◽  
Vol 9 (7) ◽  
pp. 1100-1108 ◽  
Author(s):  
Simon V. S. IpCho ◽  
Kar-Chun Tan ◽  
Geraldine Koh ◽  
Joel Gummer ◽  
Richard P. Oliver ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Carbon Metabolism ◽  
Critical Role ◽  
Central Carbon Metabolism ◽  
Stagonospora Nodorum ◽  
Amino Acid Synthesis ◽  
Content Type ◽  
Central Carbon

ABSTRACT The Stagonospora nodorum StuA transcription factor gene SnStuA was identified by homology searching in the genome of the wheat pathogen Stagonospora nodorum. Gene expression analysis revealed that SnStuA transcript abundance increased throughout infection and in vitro growth to peak during sporulation. To investigate its role, the gene was deleted by homologous recombination. The growth of the resulting mutants was retarded on glucose compared to the wild-type growth, and the mutants also failed to sporulate. Glutamate as a sole carbon source restored the growth rate defect observed on glucose, although sporulation remained impaired. The SnstuA strains were essentially nonpathogenic, with only minor growth observed around the point of inoculation. The role of SnstuA was investigated using metabolomics, which revealed that this gene's product played a key role in regulating central carbon metabolism, with glycolysis, the TCA cycle, and amino acid synthesis all affected in the mutants. SnStuA was also found to positively regulate the synthesis of the mycotoxin alternariol. Gene expression studies on the recently identified effectors in Stagonospora nodorum found that SnStuA was a positive regulator of SnTox3 but was not required for the expression of ToxA. This study has uncovered a multitude of novel regulatory targets of SnStuA and has highlighted the critical role of this gene product in the pathogenicity of Stagonospora nodorum.

scholarly journals The Essential Role of Cholesterol Metabolism in the Intracellular Survival of Mycobacterium leprae Is Not Coupled to Central Carbon Metabolism and Energy Production

2015 ◽  
Vol 197 (23) ◽  
pp. 3698-3707 ◽  
Author(s):  
Maria Angela M. Marques ◽  
Marcia Berrêdo-Pinho ◽  
Thabatta L. S. A. Rosa ◽  
Venugopal Pujari ◽  
Robertha M. R. Lemes ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Energy Production ◽  
Essential Role ◽  
Cholesterol Metabolism ◽  
Mycobacterium Leprae ◽  
Intracellular Survival ◽  
Central Carbon Metabolism ◽  
Content Type ◽  
Central Carbon

ABSTRACTMycobacterium lepraeinduces the formation of lipid droplets, which are recruited to pathogen-containing phagosomes in infected macrophages and Schwann cells. Cholesterol is among the lipids with increased abundance inM. leprae-infected cells, and intracellular survival relies on cholesterol accumulation. The present study investigated the capacity ofM. lepraeto acquire and metabolize cholesterol.In silicoanalyses showed that oxidation of cholesterol to cholest-4-en-3-one (cholestenone), the first step of cholesterol degradation catalyzed by the enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), is apparently the only portion of the cholesterol catabolic pathway seen inMycobacterium tuberculosispreserved byM. leprae. Incubation of bacteria with radiolabeled cholesterol confirmed thein silicopredictions. Radiorespirometry and lipid analyses performed after incubatingM. lepraewith [4-14C]cholesterol or [26-14C]cholesterol showed the inability of this pathogen to metabolize the sterol rings or the side chain of cholesterol as a source of energy and carbon. However, the bacteria avidly incorporated cholesterol and, as expected, converted it to cholestenone bothin vitroandin vivo. Our data indicate thatM. lepraehas lost the capacity to degrade and utilize cholesterol as a nutritional source but retains the enzyme responsible for its oxidation to cholestenone. Thus, the essential role of cholesterol metabolism in the intracellular survival ofM. lepraeis uncoupled from central carbon metabolism and energy production. Further elucidation of cholesterol metabolism in the host cell duringM. lepraeinfection will establish the mechanism by which this lipid supportsM. lepraeintracellular survival and will open new avenues for novel leprosy therapies.IMPORTANCEOur study focused on the obligate intracellular pathogenMycobacterium lepraeand its capacity to metabolize cholesterol. The data make an important contribution for those interested in understanding the mechanisms of mycobacterial pathogenesis, since they indicate that the essential role of cholesterol forM. lepraeintracellular survival does not rely on its utilization as a nutritional source. Our findings reinforce the complexity of cholesterol's role in sustainingM. lepraeinfection. Further elucidation of cholesterol metabolism in the host cell duringM. lepraeinfection will establish the mechanism by which this lipid supportsM. lepraeintracellular survival and will open new avenues for novel leprosy therapies.

scholarly journals HexR Controls Glucose-Responsive Genes and Central Carbon Metabolism in Neisseria meningitidis

2015 ◽  
Vol 198 (4) ◽  
pp. 644-654 ◽  
Author(s):  
Ana Antunes ◽  
Giacomo Golfieri ◽  
Francesca Ferlicca ◽  
Marzia M. Giuliani ◽  
Vincenzo Scarlato ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Neisseria Meningitidis ◽  
Microarray Analysis ◽  
Carbon Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Transcriptional Regulator ◽  
Central Carbon Metabolism ◽  
Binding Motif ◽  
Content Type ◽  
Central Carbon

ABSTRACTNeisseria meningitidis, an exclusively human pathogen and the leading cause of bacterial meningitis, must adapt to different host niches during human infection.N. meningitidiscan utilize a restricted range of carbon sources, including lactate, glucose, and pyruvate, whose concentrations vary in host niches. Microarray analysis ofN. meningitidisgrown in a chemically defined medium in the presence or absence of glucose allowed us to identify genes regulated by carbon source availability. Most such genes are implicated in energy metabolism and transport, and some are implicated in virulence. In particular, genes involved in glucose catabolism were upregulated, whereas genes involved in the tricarboxylic acid cycle were downregulated. Several genes encoding surface-exposed proteins, including the MafA adhesins andNeisseriasurface protein A, were upregulated in the presence of glucose. Our microarray analysis led to the identification of a glucose-responsivehexR-like transcriptional regulator that controls genes of the central carbon metabolism ofN. meningitidisin response to glucose. We characterized the HexR regulon and showed that thehexRgene is accountable for some of the glucose-responsive regulation;in vitroassays with the purified protein showed that HexR binds to the promoters of the central metabolic operons of the bacterium. Based on DNA sequence alignment of the target sites, we propose a 17-bp pseudopalindromic consensus HexR binding motif. Furthermore,N. meningitidisstrains lackinghexRexpression were deficient in establishing successful bacteremia in an infant rat model of infection, indicating the importance of this regulator for the survival of this pathogenin vivo.IMPORTANCENeisseria meningitidisgrows on a limited range of nutrients during infection. We analyzed the gene expression ofN. meningitidisin response to glucose, the main energy source available in human blood, and we found that glucose regulates many genes implicated in energy metabolism and nutrient transport, as well as some implicated in virulence. We identified and characterized a transcriptional regulator (HexR) that controls metabolic genes ofN. meningitidisin response to glucose. We generated a mutant lacking HexR and found that the mutant was impaired in causing systemic infection in animal models. SinceN. meningitidislacks known bacterial regulators of energy metabolism, our findings suggest that HexR plays a major role in its biology by regulating metabolism in response to environmental signals.

A critical role of Sp1 transcription factor in regulating gene expression in response to insulin and other hormones

Life Sciences ◽  
2008 ◽  
Vol 83 (9-10) ◽  
pp. 305-312 ◽  
Author(s):  
Solomon S. Solomon ◽  
Gipsy Majumdar ◽  
Antonio Martinez-Hernandez ◽  
Rajendra Raghow
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Critical Role ◽  
Sp1 Transcription Factor

scholarly journals Dynamic Metabolic Rewiring Enables Efficient Acetyl Coenzyme A Assimilation in Paracoccus denitrificans

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Katharina Kremer ◽  
Muriel C. F. van Teeseling ◽  
Lennart Schada von Borzyskowski ◽  
Iria Bernhardsgrütter ◽  
Rob J. M. van Spanning ◽  
...  
Keyword(s):  
Growth Rates ◽  
Carbon Metabolism ◽  
Paracoccus Denitrificans ◽  
High Growth ◽  
Central Carbon Metabolism ◽  
High Biomass ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Content Type ◽  
Central Carbon

ABSTRACT During growth, microorganisms have to balance metabolic flux between energy and biosynthesis. One of the key intermediates in central carbon metabolism is acetyl coenzyme A (acetyl-CoA), which can be either oxidized in the citric acid cycle or assimilated into biomass through dedicated pathways. Two acetyl-CoA assimilation strategies in bacteria have been described so far, the ethylmalonyl-CoA pathway (EMCP) and the glyoxylate cycle (GC). Here, we show that Paracoccus denitrificans uses both strategies for acetyl-CoA assimilation during different growth stages, revealing an unexpected metabolic complexity in the organism’s central carbon metabolism. The EMCP is constitutively expressed on various substrates and leads to high biomass yields on substrates requiring acetyl-CoA assimilation, such as acetate, while the GC is specifically induced on these substrates, enabling high growth rates. Even though each acetyl-CoA assimilation strategy alone confers a distinct growth advantage, P. denitrificans recruits both to adapt to changing environmental conditions, such as a switch from succinate to acetate. Time-resolved single-cell experiments show that during this switch, expression of the EMCP and GC is highly coordinated, indicating fine-tuned genetic programming. The dynamic metabolic rewiring of acetyl-CoA assimilation is an evolutionary innovation by P. denitrificans that allows this organism to respond in a highly flexible manner to changes in the nature and availability of the carbon source to meet the physiological needs of the cell, representing a new phenomenon in central carbon metabolism. IMPORTANCE Central carbon metabolism provides organisms with energy and cellular building blocks during growth and is considered the invariable “operating system” of the cell. Here, we describe a new phenomenon in bacterial central carbon metabolism. In contrast to many other bacteria that employ only one pathway for the conversion of the central metabolite acetyl-CoA, Paracoccus denitrificans possesses two different acetyl-CoA assimilation pathways. These two pathways are dynamically recruited during different stages of growth, which allows P. denitrificans to achieve both high biomass yield and high growth rates under changing environmental conditions. Overall, this dynamic rewiring of central carbon metabolism in P. denitrificans represents a new strategy compared to those of other organisms employing only one acetyl-CoA assimilation pathway.

scholarly journals Reproductive Potential of Yeast Cells Depends on Overall Action of Interconnected Changes in Central Carbon Metabolism, Cellular Biosynthetic Capacity, and Proteostasis

2020 ◽  
Vol 21 (19) ◽  
pp. 7313
Author(s):  
Roman Maslanka ◽  
Renata Zadrag-Tecza
Keyword(s):  
Calorie Restriction ◽  
Carbon Metabolism ◽  
Metabolic Flux ◽  
Reproductive Potential ◽  
Central Carbon Metabolism ◽  
Yeast Cells ◽  
Reproductive Capacity ◽  
Hexokinase 2 ◽  
Central Carbon

Carbon metabolism is a crucial aspect of cell life. Glucose, as the primary source of energy and carbon skeleton, determines the type of cell metabolism and biosynthetic capabilities, which, through the regulation of cell size, may affect the reproductive capacity of the yeast cell. Calorie restriction is considered as the most effective way to improve cellular physiological capacity, and its molecular mechanisms are complex and include several nutrient signaling pathways. It is widely assumed that the metabolic shift from fermentation to respiration is treated as a substantial driving force for the mechanism of calorie restriction and its influence on reproductive capabilities of cells. In this paper, we propose another approach to this issue based on analysis the connection between energy-producing and biomass formation pathways which are closed in the metabolic triangle, i.e., the respiration-glycolysis-pentose phosphate pathway. The analyses were based on the use of cells lacking hexokinase 2 (∆hxk2) and conditions of different glucose concentration corresponding to the calorie restriction and the calorie excess. Hexokinase 2 is the key enzyme involved in central carbon metabolism and is also treated as a calorie restriction mimetic. The experimental model used allows us to explain both the role of increased respiration as an effect of calorie restriction but also other aspects of carbon metabolism and the related metabolic flux in regulation of reproductive potential of the cells. The obtained results reveal that increased respiration is not a prerequisite for reproductive potential extension but rather an accompanying effect of the positive role of calorie restriction. More important seems to be the changes connected with fluxes in central carbon metabolic pathways resulting in low biosynthetic capabilities and improved proteostasis.

scholarly journals The Functional Structure of Central Carbon Metabolism in Pseudomonas putida KT2440

2014 ◽  
Vol 80 (17) ◽  
pp. 5292-5303 ◽  
Author(s):  
Suresh Sudarsan ◽  
Sarah Dethlefsen ◽  
Lars M. Blank ◽  
Martin Siemann-Herzberg ◽  
Andreas Schmid
Keyword(s):  
Pseudomonas Putida ◽  
Carbon Metabolism ◽  
Carbon Sources ◽  
Central Carbon Metabolism ◽  
Transcriptional Level ◽  
Regulation Mechanism ◽  
Central Metabolism ◽  
Content Type ◽  
Central Carbon ◽  
Definition Of

ABSTRACTWhat defines central carbon metabolism? The classic textbook scheme of central metabolism includes the Embden-Meyerhof-Parnas (EMP) pathway of glycolysis, the pentose phosphate pathway, and the citric acid cycle. The prevalence of this definition of central metabolism is, however, equivocal without experimental validation. We address this issue using a general experimental approach that combines the monitoring of transcriptional and metabolic flux changes between steady states on alternative carbon sources. This approach is investigated by using the model bacteriumPseudomonas putidawith glucose, fructose, and benzoate as carbon sources. The catabolic reactions involved in the initial uptake and metabolism of these substrates are expected to show a correlated change in gene expressions and metabolic fluxes. However, there was no correlation for the reactions linking the 12 biomass precursor molecules, indicating a regulation mechanism other than mRNA synthesis for central metabolism. This result substantiates evidence for a (re)definition of central carbon metabolism including all reactions that are bound to tight regulation and transcriptional invariance. Contrary to expectations, the canonical Entner-Doudoroff and EMP pathwayssensu strictoare not a part of central carbon metabolism inP. putida, as they are not regulated differently from the aromatic degradation pathway. The regulatory analyses presented here provide leads on a qualitative basis to address the use of alternative carbon sources by deregulation and overexpression at the transcriptional level, while rate improvements in central carbon metabolism require careful adjustment of metabolite concentrations, as regulation resides to a large extent in posttranslational and/or metabolic regulation.

scholarly journals IntracellularStaphylococcus aureusModulates Host Central Carbon Metabolism To Activate Autophagy

mSphere ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. e00374-18 ◽  
Author(s):  
Natalia Bravo-Santano ◽  
James K. Ellis ◽  
Luis M. Mateos ◽  
Yolanda Calle ◽  
Hector C. Keun ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Cell ◽  
Carbon Metabolism ◽  
Central Carbon Metabolism ◽  
Metabolic Changes ◽  
Autophagic Flux ◽  
Content Type ◽  
Central Carbon ◽  
Infected Cells ◽  
Intracellular Proliferation

ABSTRACTStaphylococcus aureusis a facultative intracellular pathogen that invades and replicates within many types of phagocytic and nonphagocytic cells. During intracellular infection,S. aureusis capable of subverting xenophagy and escaping to the cytosol of the host cell. Furthermore, drug-induced autophagy facilitates the intracellular replication ofS. aureus, but the reasons behind this are unclear. Here, we have studied the host central carbon metabolism duringS. aureusintracellular infection. We found extensive metabolic rerouting and detected several distinct metabolic changes that suggested starvation-induced autophagic flux in infected cells. These changes included increased uptake but lower intracellular levels of glucose and low abundance of several essential amino acids, as well as markedly upregulated glutaminolysis. Furthermore, we show that AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinase (ERK) phosphorylation levels are significantly increased in infected cells. Interestingly, while autophagy was activated in response toS. aureusinvasion, most of the autophagosomes detected in infected cells did not contain bacteria, suggesting thatS. aureusinduces the autophagic flux during cell invasion for energy generation and nutrient scavenging. Accordingly, AMPK inhibition haltedS. aureusintracellular proliferation.IMPORTANCEStaphylococcus aureusescapes from immune recognition by invading a wide range of human cells. Once the pathogen becomes intracellular, the most important last resort antibiotics are not effective. Therefore, novel anti-infective therapies against intracellularS. aureusare urgently needed. Here, we have studied the physiological changes induced in the host cells byS. aureusduring its intracellular proliferation. This is important, because the pathogen exploits the host cell’s metabolism for its own proliferation. We find thatS. aureusseverely depletes glucose and amino acid pools, which leads to increased breakdown of glutamine by the host cell in an attempt to meet its own metabolic needs. All of these metabolic changes activate autophagy in the host cell for nutrient scavenging and energy generation. The metabolic activation of autophagy could be used by the pathogen to sustain its own intracellular survival, making it an attractive target for novel anti-infectives.

scholarly journals Airpnp: Auto- and Integrated Regulation of Polynucleotide Phosphorylase

2015 ◽  
Vol 197 (24) ◽  
pp. 3748-3750 ◽  
Author(s):  
Ciarán Condon
Keyword(s):  
Gene Expression ◽  
Carbon Metabolism ◽  
Rna Degradation ◽  
Central Carbon Metabolism ◽  
Polynucleotide Phosphorylase ◽  
Link Type ◽  
Central Carbon ◽  
Integrated Regulation ◽  
Complex Regulation ◽  
Posttranscriptional Level

The properties and expression of polynucleotide phosphorylase (PNPase), capable of both RNA degradation and polymerization, have been studied for 60 years. In this issue of theJournal of Bacteriology,Park et al.(H. Park, H. Yakhnin, M. Connolly, T. Romeo, and P. Babitzke, J Bacteriol 197:3751–3759, 2015,http://dx.doi.org/10.1128/JB.00721-15) write the latest chapter on the complex regulation ofpnpgene expression involving CsrA. I describe how this new piece of the puzzle fits into the global scheme of PNPase autoregulation and how this is influenced by central carbon metabolism at both the posttranscriptional level and that of enzyme activity.

scholarly journals Transcriptomic Analysis of the Influence of Methanol Assimilation on the Gene Expression in the Recombinant Pichia pastoris Producing Hirudin Variant 3

Genes ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 606 ◽  
Author(s):  
Li ◽  
Ma ◽  
Xu ◽  
Wang ◽  
Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Pichia Pastoris ◽  
Carbon Metabolism ◽  
Fermentation Broth ◽  
Alcohol Oxidase ◽  
Central Carbon Metabolism ◽  
Recombinant Pichia Pastoris ◽  
Central Carbon ◽  
Almost All

Hirudin and its variants, as strong inhibitors against thrombin, are present in the saliva of leeches and are recognized as potent anticoagulants. However, their yield is far from the clinical requirement up to now. In this study, the production of hirudin variant 3 (HV3) was successfully realized by cultivating the recombinant Pichia pastoris GS115/pPIC9K-hv3 under the regulation of the promoter of AOX1 encoding alcohol oxidase (AOX). The antithrombin activity in the fermentation broth reached the maximum value of 5000 ATU/mL. To explore an effective strategy for improving HV3 production in the future, we investigated the influence of methanol assimilation on the general gene expression in this recombinant by transcriptomic study. The results showed that methanol was partially oxidized into CO2, and the rest was converted into glycerone-P which subsequently entered into central carbon metabolism, energy metabolism, and amino acid biosynthesis. However, the later metabolic processes were almost all down-regulated. Therefore, we propose that the up-regulated central carbon metabolism, energy, and amino acid metabolism should be beneficial for methanol assimilation, which would accordingly improve the production of HV3.

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