scholarly journals GntR Family Regulator DasR Controls Acetate Assimilation by Directly Repressing the acsA Gene in Saccharopolyspora erythraea

2018 ◽  
Vol 200 (13) ◽  
Author(s):  
Di You ◽  
Bai-Qing Zhang ◽  
Bang-Ce Ye
Keyword(s):  
Environmental Changes ◽  
Carbon Sources ◽  
Saccharopolyspora Erythraea ◽  
Upstream Region ◽  
Acetate Metabolism ◽  
Acetyl Coa ◽  
Content Type ◽  
Acetate Assimilation ◽  
Responsive Element ◽  
Gntr Family

ABSTRACT The GntR family regulator DasR controls the transcription of genes involved in chitin and N -acetylglucosamine (GlcNAc) metabolism in actinobacteria. GlcNAc is catabolized to ammonia, fructose-6-phosphate (Fru-6P), and acetate, which are nitrogen and carbon sources. In this work, a DasR-responsive element ( dre ) was observed in the upstream region of acsA1 in Saccharopolyspora erythraea . This gene encodes acetyl coenzyme A (acetyl-CoA) synthetase (Acs), an enzyme that catalyzes the conversion of acetate into acetyl-CoA. We found that DasR repressed the transcription of acsA1 in response to carbon availability, especially with GlcNAc. Growth inhibition was observed in a dasR -deleted mutant (Δ dasR ) in the presence of GlcNAc in minimal medium containing 10 mM acetate, a condition under which Acs activity is critical to growth. These results demonstrate that DasR controls acetate assimilation by directly repressing the transcription of the acsA1 gene and performs regulatory roles in the production of intracellular acetyl-CoA in response to GlcNAc. IMPORTANCE Our work has identified the DasR GlcNAc-sensing regulator that represses the generation of acetyl-CoA by controlling the expression of acetyl-CoA synthetase, an enzyme responsible for acetate assimilation in S. erythraea . The finding provides the first insights into the importance of DasR in the regulation of acetate metabolism, which encompasses the regulatory network between nitrogen and carbon metabolism in actinobacteria, in response to environmental changes.

scholarly journals Controlled Gene Expression in Bifidobacteria by Use of a Bile-Responsive Element

2011 ◽  
Vol 78 (2) ◽  
pp. 581-585 ◽  
Author(s):  
Lorena Ruiz ◽  
Pablo Álvarez-Martín ◽  
Baltasar Mayo ◽  
Clara G. de los Reyes-Gavilán ◽  
Miguel Gueimonde ◽  
...  
Keyword(s):  
Bile Salts ◽  
Promoter Activity ◽  
Bifidobacterium Longum ◽  
Upstream Region ◽  
Surface Acting ◽  
Content Type ◽  
Reporter Activity ◽  
Responsive Element ◽  
Inducible Gene

ABSTRACTThe promoter activity of the upstream region of the bile-inducible genebetAfromBifidobacterium longumsubsp.longumNCC2705 was characterized. DNA fragments were cloned into the reporter vector pMDYAbfB, and the arabinofuranosidase activity was determined under differentin vitroconditions. A segment of 469 bp was found to be the smallest operational unit that retains bile inducibility. The reporter activity was strongly affected by the presence of ox gall, cholate, and conjugated cholate, but not by other bile salts and cell-surface-acting compounds. Remarkably, this bile-inducible system was also active in other bifidobacteria containingbetAhomologs.

scholarly journals Reciprocal Regulation of GlnR and PhoP in Response to Nitrogen and Phosphate Limitations in Saccharopolyspora erythraea

2015 ◽  
Vol 82 (1) ◽  
pp. 409-420 ◽  
Author(s):  
Li-li Yao ◽  
Bang-Ce Ye
Keyword(s):  
Cross Talk ◽  
Binding Sites ◽  
Environmental Changes ◽  
Streptomyces Coelicolor ◽  
Saccharopolyspora Erythraea ◽  
Phosphate Metabolism ◽  
Promoter Regions ◽  
Reciprocal Regulation ◽  
Content Type ◽  
Phosphate Source

ABSTRACTNitrogen and phosphate source sensing, uptake, and assimilation are essential for the growth and development of microorganisms. In this study, we demonstrated that SACE_6965 encodes the phosphate regulator PhoP, which controls the transcription of genes involved in phosphate metabolism in the erythromycin-producingSaccharopolyspora erythraea. We found that PhoP and the nitrogen regulator GlnR both regulate the transcription ofglnRas well as other nitrogen metabolism-related genes. Interestingly, both GlnR- and PhoP-binding sites were identified in thephoPpromoter region. Unlike the nonreciprocal regulation of GlnR and PhoP observed inStreptomyces coelicolorandStreptomyces lividans, GlnR negatively controls the transcription of thephoPgene inS. erythraea. This suggests that GlnR directly affects phosphate metabolism and demonstrates that the cross talk between GlnR and PhoP is reciprocal. Although GlnR and PhoP sites in theglnRandphoPpromoter regions are located in close proximity to one another (separated by only 2 to 4 bp), the binding of both regulators to their respective region was independent and noninterfering. These results indicate that two regulators could separately bind to their respective binding sites and control nitrogen and phosphate metabolism in response to environmental changes. The reciprocal cross talk observed between GlnR and PhoP serves as a foundation for understanding the regulation of complex primary and secondary metabolism in antibiotic-producing actinomycetes.

scholarly journals Acetate Dissimilation and Assimilation in Mycobacterium tuberculosis Depend on Carbon Availability

2015 ◽  
Vol 197 (19) ◽  
pp. 3182-3190 ◽  
Author(s):  
Nadine Rücker ◽  
Sandra Billig ◽  
René Bücker ◽  
Dieter Jahn ◽  
Christoph Wittmann ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Mycobacterium Tuberculosis ◽  
Enzymatic Reaction ◽  
Acetate Metabolism ◽  
Carbon Substrate ◽  
Dual Function ◽  
Acetyl Coa ◽  
Excess Carbon ◽  
Content Type ◽  
Acetate Formation

ABSTRACTMycobacterium tuberculosispersists inside granulomas in the human lung. Analysis of the metabolic composition of granulomas from guinea pigs revealed that one of the organic acids accumulating in the course of infection is acetate (B. S. Somashekar, A. G. Amin, C. D. Rithner, J. Troudt, R. Basaraba, A. Izzo, D. C. Crick, and D. Chatterjee, J Proteome Res 10:4186–4195, 2011, doi:http://dx.doi.org/10.1021/pr2003352), which might result either from metabolism of the pathogen or might be provided by the host itself. Our studies characterize a metabolic pathway by whichM. tuberculosisgenerates acetate in the cause of fatty acid catabolism. The acetate formation depends on the enzymatic activities of Pta and AckA. Using actyl coenzyme A (acetyl-CoA) as a substrate, acetyl-phosphate is generated and finally dephosphorylated to acetate, which is secreted into the medium. Knockout mutants lacking either theptaorackAgene showed significantly reduced acetate production when grown on fatty acids. This effect is even more pronounced when the glyoxylate shunt is blocked, resulting in higher acetate levels released to the medium. The secretion of acetate was followed by an assimilation of the metabolite when other carbon substrates became limiting. Our data indicate that during acetate assimilation, the Pta-AckA pathway acts in concert with another enzymatic reaction, namely, the acetyl-CoA synthetase (Acs) reaction. Thus, acetate metabolism might possess a dual function, mediating an overflow reaction to release excess carbon units and resumption of acetate as a carbon substrate.IMPORTANCEDuring infection, host-derived lipid components present the major carbon source at the infection site. β-Oxidation of fatty acids results in the formation of acetyl-CoA. In this study, we demonstrate that consumption of fatty acids byMycobacterium tuberculosisactivates an overflow mechanism, causing the pathogen to release excess carbon intermediates as acetate. The Pta-AckA pathway mediating acetate formation proved to be reversible, enablingM. tuberculosisto reutilize the previously secreted acetate as a carbon substrate for metabolism.

scholarly journals Intracellular Acetyl Unit Transport in Fungal Carbon Metabolism

2010 ◽  
Vol 9 (12) ◽  
pp. 1809-1815 ◽  
Author(s):  
Karin Strijbis ◽  
Ben Distel
Keyword(s):  
Carbon Metabolism ◽  
Citrate Synthase ◽  
Current Knowledge ◽  
Glyoxylate Cycle ◽  
Carbon Sources ◽  
Fungal Species ◽  
Special Focus ◽  
Acetyl Coa ◽  
Content Type ◽  
Dependent Pathway

ABSTRACT Acetyl coenzyme A (acetyl-CoA) is a central metabolite in carbon and energy metabolism. Because of its amphiphilic nature and bulkiness, acetyl-CoA cannot readily traverse biological membranes. In fungi, two systems for acetyl unit transport have been identified: a shuttle dependent on the carrier carnitine and a (peroxisomal) citrate synthase-dependent pathway. In the carnitine-dependent pathway, carnitine acetyltransferases exchange the CoA group of acetyl-CoA for carnitine, thereby forming acetyl-carnitine, which can be transported between subcellular compartments. Citrate synthase catalyzes the condensation of oxaloacetate and acetyl-CoA to form citrate that can be transported over the membrane. Since essential metabolic pathways such as fatty acid β-oxidation, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle are physically separated into different organelles, shuttling of acetyl units is essential for growth of fungal species on various carbon sources such as fatty acids, ethanol, acetate, or citrate. In this review we summarize the current knowledge on the different systems of acetyl transport that are operational during alternative carbon metabolism, with special focus on two fungal species: Saccharomyces cerevisiae and Candida albicans.

scholarly journals The Crabtree Effect Shapes theSaccharomyces cerevisiaeLag Phase during the Switch between Different Carbon Sources

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Gemma Perez-Samper ◽  
Bram Cerulus ◽  
Abbas Jariani ◽  
Lieselotte Vermeersch ◽  
Nuria Barrajón Simancas ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Carbon Sources ◽  
Anaerobic Growth ◽  
Lag Phase ◽  
Crabtree Effect ◽  
Molecular Processes ◽  
Content Type ◽  
A Genome ◽  
Growth Experiments ◽  
Lag Phases

ABSTRACTWhen faced with environmental changes, microbes often enter a temporary growth arrest during which they reprogram the expression of specific genes to adapt to the new conditions. A prime example of such a lag phase occurs when microbes need to switch from glucose to other, less-preferred carbon sources. Despite its industrial relevance, the genetic network that determines the duration of the lag phase has not been studied in much detail. Here, we performed a genome-wide Bar-Seq screen to identify genetic determinants of theSaccharomyces cerevisiaeglucose-to-galactose lag phase. The results show that genes involved in respiration, and specifically those encoding complexes III and IV of the electron transport chain, are needed for efficient growth resumption after the lag phase. Anaerobic growth experiments confirmed the importance of respiratory energy conversion in determining the lag phase duration. Moreover, overexpression of the central regulator of respiration,HAP4, leads to significantly shorter lag phases. Together, these results suggest that the glucose-induced repression of respiration, known as the Crabtree effect, is a major determinant of microbial fitness in fluctuating carbon environments.IMPORTANCEThe lag phase is arguably one of the prime characteristics of microbial growth. Longer lag phases result in lower competitive fitness in variable environments, and the duration of the lag phase is also important in many industrial processes where long lag phases lead to sluggish, less efficient fermentations. Despite the immense importance of the lag phase, surprisingly little is known about the exact molecular processes that determine its duration. Our study uses the molecular toolbox ofS. cerevisiaecombined with detailed growth experiments to reveal how the transition from fermentative to respirative metabolism is a key bottleneck for cells to overcome the lag phase. Together, our findings not only yield insight into the key molecular processes and genes that influence lag duration but also open routes to increase the efficiency of industrial fermentations and offer an experimental framework to study other types of lag behavior.

scholarly journals Modulation of CrbS-Dependent Activation of the Acetate Switch inVibrio cholerae

2018 ◽  
Vol 200 (23) ◽  
Author(s):  
Itai Muzhingi ◽  
Cecilia Prado ◽  
Mariame Sylla ◽  
Frances F. Diehl ◽  
Duy K. Nguyen ◽  
...  
Keyword(s):  
Response Regulator ◽  
Environmental Variable ◽  
Nutrient Sensing ◽  
Host Recognition ◽  
Receptor Protein ◽  
Acetate Metabolism ◽  
System Control ◽  
Acetyl Coa ◽  
Content Type ◽  
Camp Receptor

ABSTRACTVibrio choleraecontrols the pathogenicity of interactions with arthropod hosts via the activity of the CrbS/R two-component system. This signaling pathway regulates the consumption of acetate, which in turn alters the relative virulence of interactions with arthropods, includingDrosophila melanogaster. CrbS is a histidine kinase that links a transporter-like domain to its signaling apparatus via putative STAC and PAS domains. CrbS and its cognate response regulator are required for the expression of acetyl coenzyme A (acetyl-CoA) synthetase (product ofacs), which converts acetate to acetyl-CoA. We demonstrate that the STAC domain of CrbS is required for signaling in culture; without it,acstranscription is reduced in LB medium, andV. choleraecannot grow on acetate minimal media. However, the strain remains virulent towardDrosophilaand expressesacssimilarly to the wild type during infection. This suggests that there is a unique signal or environmental variable that modulates CrbS in the gastrointestinal tract ofDrosophila. Second, we present evidence in support of CrbR, the response regulator that interacts with CrbS, binding directly to theacspromoter, and we identify a region of the promoter that CrbR may target. We further demonstrate that nutrient signals, together with the cAMP receptor protein (CRP)-cAMP system, controlacstranscription, but regulation may occur indirectly, as CRP-cAMP activates the expression of thecrbSandcrbRgenes. Finally, we define the role of the Pta-AckA system inV. choleraeand identify redundancy built into acetate excretion pathways in this pathogen.IMPORTANCECrbS is a member of a unique family of sensor histidine kinases, as its structure suggests that it may link signaling to the transport of a molecule. However, mechanisms through which CrbS senses and communicates information about the outside world are unknown. In theVibrionaceae, orthologs of CrbS regulate acetate metabolism, which can, in turn, affect interactions with host organisms. Here, we situate CrbS within a larger regulatory framework, demonstrating thatcrbSis regulated by nutrient-sensing systems. Furthermore, CrbS domains may play various roles in signaling during infection and growth in culture, suggesting a unique mechanism of host recognition. Finally, we define the roles of additional pathways in acetate flux, as a foundation for further studies of this metabolic nexus point.

scholarly journals Malate Synthase and β-Methylmalyl Coenzyme A Lyase Reactions in the Methylaspartate Cycle in Haloarcula hispanica

2016 ◽  
Vol 199 (4) ◽  
Author(s):  
Farshad Borjian ◽  
Jing Han ◽  
Jing Hou ◽  
Hua Xiang ◽  
Jan Zarzycki ◽  
...  
Keyword(s):  
Coenzyme A ◽  
Malate Synthase ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Physiological Functions ◽  
Content Type ◽  
Acetate Assimilation ◽  
Acetyl Coenzyme ◽  
Haloarcula Hispanica ◽  
Anaplerotic Pathway

ABSTRACT Haloarchaea are extremely halophilic heterotrophic microorganisms belonging to the class Halobacteria (Euryarchaeota). Almost half of the haloarchaea possesses the genes coding for enzymes of the methylaspartate cycle, a recently discovered anaplerotic acetate assimilation pathway. In this cycle, the enzymes of the tricarboxylic acid cycle together with the dedicated enzymes of the methylaspartate cycle convert two acetyl coenzyme A (acetyl-CoA) molecules to malate. The methylaspartate cycle involves two reactions catalyzed by homologous enzymes belonging to the CitE-like enzyme superfamily, malyl-CoA lyase/thioesterase (haloarchaeal malate synthase [hMS]; Hah_2476 in Haloarcula hispanica) and β-methylmalyl-CoA lyase (haloarchaeal β-methylmalyl-CoA lyase [hMCL]; Hah_1341). Although both enzymes catalyze the same reactions, hMS was previously proposed to preferentially catalyze the formation of malate from acetyl-CoA and glyoxylate (malate synthase activity) and hMCL was proposed to primarily cleave β-methylmalyl-CoA to propionyl-CoA and glyoxylate. Here we studied the physiological functions of these enzymes during acetate assimilation in H. hispanica by using biochemical assays of the wild type and deletion mutants. Our results reveal that the main physiological function of hMS is malyl-CoA (not malate) formation and that hMCL catalyzes a β-methylmalyl-CoA lyase reaction in vivo. The malyl-CoA thioesterase activities of both enzymes appear to be not essential for growth on acetate. Interestingly, despite the different physiological functions of hMS and hMCL, structural comparisons predict that these two proteins have virtually identical active sites, thus highlighting the need for experimental validation of their catalytic functions. Our results provide further proof of the operation of the methylaspartate cycle and indicate the existence of a distinct, yet-to-be-discovered malyl-CoA thioesterase in haloarchaea. IMPORTANCE Acetate is one of the most important substances in natural environments. The activated form of acetate, acetyl coenzyme A (acetyl-CoA), is the high-energy intermediate at the crossroads of central metabolism: its oxidation generates energy for the cell, and about a third of all biosynthetic fluxes start directly from acetyl-CoA. Many organic compounds enter the central carbon metabolism via this key molecule. To sustain growth on acetyl-CoA-generating compounds, a dedicated assimilation (anaplerotic) pathway is required. The presence of an anaplerotic pathway is a prerequisite for growth in many environments, being important for environmentally, industrially, and clinically important microorganisms. Here we studied specific reactions of a recently discovered acetate assimilation pathway, the methylaspartate cycle, functioning in extremely halophilic archaea.

scholarly journals ATP-Citrate Lyase Is Required for Production of Cytosolic Acetyl Coenzyme A and Development in Aspergillus nidulans

2010 ◽  
Vol 9 (7) ◽  
pp. 1039-1048 ◽  
Author(s):  
Michael J. Hynes ◽  
Sandra L. Murray
Keyword(s):  
Aspergillus Nidulans ◽  
Coenzyme A ◽  
Carbon Sources ◽  
Gene Arrangement ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Content Type ◽  
Acetyl Coenzyme ◽  
Citrate Lyase

ABSTRACT Acetyl coenzyme A (CoA) is a central metabolite in carbon and energy metabolism and in the biosynthesis of cellular molecules. A source of cytoplasmic acetyl-CoA is essential for the production of fatty acids and sterols and for protein acetylation, including histone acetylation in the nucleus. In Saccharomyces cerevisiae and Candida albicans acetyl-CoA is produced from acetate by cytoplasmic acetyl-CoA synthetase, while in plants and animals acetyl-CoA is derived from citrate via ATP-citrate lyase. In the filamentous ascomycete Aspergillus nidulans, tandem divergently transcribed genes (aclA and aclB) encode the subunits of ATP-citrate lyase, and we have deleted these genes. Growth is greatly diminished on carbon sources that do not result in cytoplasmic acetyl-CoA, such as glucose and proline, while growth is not affected on carbon sources that result in the production of cytoplasmic acetyl-CoA, such as acetate and ethanol. Addition of acetate restores growth on glucose or proline, and this is dependent on facA, which encodes cytoplasmic acetyl-CoA synthetase, but not on the regulatory gene facB. Transcription of aclA and aclB is repressed by growth on acetate or ethanol. Loss of ATP-citrate lyase results in severe developmental effects, with the production of asexual spores (conidia) being greatly reduced and a complete absence of sexual development. This is in contrast to Sordaria macrospora, in which fruiting body formation is initiated but maturation is defective in an ATP-citrate lyase mutant. Addition of acetate does not repair these defects, indicating a specific requirement for high levels of cytoplasmic acetyl-CoA during differentiation. Complementation in heterokaryons between aclA and aclB deletions for all phenotypes indicates that the tandem gene arrangement is not essential.

scholarly journals Cyclic AMP (cAMP) Receptor Protein-cAMP Complex Regulates Heparosan Production in Escherichia coli Strain Nissle 1917

2015 ◽  
Vol 81 (22) ◽  
pp. 7687-7696 ◽  
Author(s):  
Huihui Yan ◽  
Feifei Bao ◽  
Liping Zhao ◽  
Yanying Yu ◽  
Jiaqin Tang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cyclic Amp ◽  
Carbon Sources ◽  
Coli Strain ◽  
Site Directed Mutagenesis ◽  
Receptor Protein ◽  
Upstream Region ◽  
Camp Receptor Protein ◽  
Content Type ◽  
Camp Receptor

ABSTRACTHeparosan serves as the starting carbon backbone for the chemoenzymatic synthesis of heparin, a widely used clinical anticoagulant drug. The availability of heparosan is a significant concern for the cost-effective synthesis of bioengineered heparin. The carbon source is known as the pivotal factor affecting heparosan production. However, the mechanism by which carbon sources control the biosynthesis of heparosan is unclear. In this study, we found that the biosynthesis of heparosan was influenced by different carbon sources. Glucose inhibits the biosynthesis of heparosan, while the addition of either fructose or mannose increases the yield of heparosan. Further study demonstrated that the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex binds to the upstream region of the region 3 promoter and stimulates the transcription of the gene cluster for heparosan biosynthesis. Site-directed mutagenesis of the CRP binding site abolished its capability of binding CRP and eliminated the stimulative effect on transcription.1H nuclear magnetic resonance (NMR) analysis was further performed to determine theEscherichia colistrain Nissle 1917 (EcN) heparosan structure and quantify extracellular heparosan production. Our results add to the understanding of the regulation of heparosan biosynthesis and may contribute to the study of other exopolysaccharide-producing strains.

scholarly journals Phyllobacterium loti sp. nov. isolated from nodules of Lotus corniculatus

2014 ◽  
Vol 64 (Pt_3) ◽  
pp. 781-786 ◽  
Author(s):  
Maximo Sánchez ◽  
Martha-Helena Ramírez-Bahena ◽  
Alvaro Peix ◽  
María J. Lorite ◽  
Juan Sanjuán ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Sequence Similarity ◽  
Carbon Sources ◽  
Lotus Corniculatus ◽  
Culture Conditions ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
The 16S Rrna Gene

Strain S658T was isolated from a Lotus corniculatus nodule in a soil sample obtained in Uruguay. Phylogenetic analysis of the 16S rRNA gene and atpD gene showed that this strain clustered within the genus Phyllobacterium . The closest related species was, in both cases, Phyllobacterium trifolii PETP02T with 99.8 % sequence similarity in the 16S rRNA gene and 96.1 % in the atpD gene. The 16S rRNA gene contains an insert at the beginning of the sequence that has no similarities with other inserts present in the same gene in described rhizobial species. Ubiquinone Q-10 was the only quinone detected. Strain S658T differed from its closest relatives through its growth in diverse culture conditions and in the assimilation of several carbon sources. It was not able to reproduce nodules in Lotus corniculatus. The results of DNA–DNA hybridization, phenotypic tests and fatty acid analyses confirmed that this strain should be classified as a representative of a novel species of the genus Phyllobacterium , for which the name Phyllobacterium loti sp. nov. is proposed. The type strain is S658T( = LMG 27289T = CECT 8230T).

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