scholarly journals Uncovering the Role of PhzC as DAHP Synthase in Shikimate Pathway of Pseudomonas chlororaphis HT66

Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 86
Author(s):  
Songwei Wang ◽  
Dongliang Liu ◽  
Muhammad Bilal ◽  
Wei Wang ◽  
Xuehong Zhang
Keyword(s):  
Feedback Inhibition ◽  
Critical Role ◽  
Shikimate Pathway ◽  
Aromatic Amino Acids ◽  
Pseudomonas Chlororaphis ◽  
Dahp Synthase ◽  
E Coli ◽  
Allosteric Control ◽  
Loop Region

DAHP synthase catalyzes the first step in the shikimate pathway, deriving the biosynthesis of aromatic amino acids (Trp, Phe and Tyr), phenazine-1-carboxamide, folic acid, and ubiquinone in Pseudomonas chlororaphis. In this study, we identified and characterized one DAHP synthase encoding gene phzC, which differs from the reported DAHP synthase encoding genes aroF, aroG and aroH in E. coli. PhzC accounts for approximately 90% of the total DAHP synthase activities in P. chlororaphis HT66 and plays the most critical role in four DAHP synthases in the shikimate pathway. Inactivation of phzC resulted in the reduction of PCN production by more than 90%, while the absence of genes aroF, aroG and aroH reduced PCN yield by less than 15%, and the production of PCN was restored after the complementation of gene phzC. Moreover, the results showed that phzC in P. chlororaphis HT66 is not sensitive to feedback inhibition. This study demonstrated that gene phzC is essential for PCN biosynthesis. The expression level of both phzC and phzE genes are not inhibited in feedback by PCN production due to the absence of a loop region required for allosteric control reaction. This study highlighted the importance of PhzC and applying P. chlororaphis for shikimate pathway-derived high-value biological production.

scholarly journals Corynebacterium glutamicum Contains 3-Deoxy-d-Arabino-Heptulosonate 7-Phosphate Synthases That Display Novel Biochemical Features

2008 ◽  
Vol 74 (17) ◽  
pp. 5497-5503 ◽  
Author(s):  
Ya-Jun Liu ◽  
Pan-Pan Li ◽  
Ke-Xin Zhao ◽  
Bao-Jun Wang ◽  
Cheng-Ying Jiang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Corynebacterium Glutamicum ◽  
Feedback Inhibition ◽  
Shikimate Pathway ◽  
Aromatic Amino Acids ◽  
Cloning And Expression ◽  
Dahp Synthase ◽  
E Coli ◽  
Phenotypic Alteration ◽  
In The Wild

ABSTRACT 3-Deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase (EC 2.5.1.54) catalyzes the first step of the shikimate pathway that finally leads to the biosynthesis of aromatic amino acids phenylalanine (Phe), tryptophan (Trp), and tyrosine (Tyr). In Corynebacterium glutamicum ATCC 13032, two chromosomal genes, NCgl0950 (aroF) and NCgl2098 (aroG), were located that encode two putative DAHP synthases. The deletion of NCgl2098 resulted in the loss of the ability of C. glutamicum RES167 (a restriction-deficient strain derived from C. glutamicum ATCC 13032) to grow in mineral medium; however, the deletion of NCgl0950 did not result in any observable phenotypic alteration. Analysis of DAHP synthase activities in the wild type and mutants of C. glutamicum RES167 indicated that NCgl2098, rather than NCgl0950, was involved in the biosynthesis of aromatic amino acids. Cloning and expression in Escherichia coli showed that both NCgl0950 and NCgl2098 encoded active DAHP synthases. Both the NCgl0950 and NCgl2098 DAHP synthases were purified from recombinant E. coli cells and characterized. The NCgl0950 DAHP synthase was sensitive to feedback inhibition by Tyr and, to a much lesser extent, by Phe and Trp. The NCgl2098 DAHP synthase was slightly sensitive to feedback inhibition by Trp, but not sensitive to Tyr and Phe, findings that were in contrast to the properties of previously known DAHP synthases from C. glutamicum subsp. flavum. Both Co2+ and Mn2+ significantly stimulated the NCgl0950 DAHP synthase's activity, whereas Mn2+ was much more stimulatory than Co2+ to the NCgl2098 DAHP synthase's activity.

SATP (YaaH), a succinate–acetate transporter protein in Escherichia coli

2013 ◽  
Vol 454 (3) ◽  
pp. 585-595 ◽  
Author(s):  
Joana Sá-Pessoa ◽  
Sandra Paiva ◽  
David Ribas ◽  
Inês Jesus Silva ◽  
Sandra Cristina Viegas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Succinic Acid ◽  
Critical Role ◽  
Amino Acid Residues ◽  
E Coli ◽  
Transporter Protein ◽  
Affinity Constants ◽  
In Trans

In the present paper we describe a new carboxylic acid transporter in Escherichia coli encoded by the gene yaaH. In contrast to what had been described for other YaaH family members, the E. coli transporter is highly specific for acetic acid (a monocarboxylate) and for succinic acid (a dicarboxylate), with affinity constants at pH 6.0 of 1.24±0.13 mM for acetic acid and 1.18±0.10 mM for succinic acid. In glucose-grown cells the ΔyaaH mutant is compromised for the uptake of both labelled acetic and succinic acids. YaaH, together with ActP, described previously as an acetate transporter, affect the use of acetic acid as sole carbon and energy source. Both genes have to be deleted simultaneously to abolish acetate transport. The uptake of acetate and succinate was restored when yaaH was expressed in trans in ΔyaaH ΔactP cells. We also demonstrate the critical role of YaaH amino acid residues Leu131 and Ala164 on the enhanced ability to transport lactate. Owing to its functional role in acetate and succinate uptake we propose its assignment as SatP: the Succinate–Acetate Transporter Protein.

The critical role of light in moderating microbial stress due to mixtures of engineered nanomaterials

2018 ◽  
Vol 5 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Carolyn M. Wilke ◽  
Jean-François Gaillard ◽  
Kimberly A. Gray
Keyword(s):  
Critical Role ◽  
Engineered Nanomaterials ◽  
Metal Nanoparticle ◽  
Toxic Effects ◽  
Solar Irradiation ◽  
Localized Surface Plasmon ◽  
E Coli ◽  
Simulated Solar Irradiation ◽  
Role Of Light

Light influences chemical interactions of engineered nanomaterials and their toxic effects. Under simulated solar irradiation, we observed that binary mixtures of n-Ag, n-Au, or n-Pt with n-TiO2cause synergistic toxic effects inE. colidue to photochemical interactions governed by metal nanoparticle stability and localized surface plasmon resonance.

Critical Role of Zinc Ion on E. coli Glutamyl-Queuosine-tRNAAsp Synthetase (Glu-Q-RS) Structure and Function

2014 ◽  
Vol 33 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Sutapa Ray ◽  
Victor Banerjee ◽  
Mickael Blaise ◽  
Baisakhi Banerjee ◽  
Kali Pada Das ◽  
...  
Keyword(s):  
Critical Role ◽  
Zinc Ion ◽  
Structure And Function ◽  
E Coli ◽  
And Function

scholarly journals Association of ω with the C-Terminal Region of the β′ Subunit Is Essential for Assembly of RNA Polymerase in Mycobacterium tuberculosis

2018 ◽  
Vol 200 (12) ◽  
Author(s):  
Chunyou Mao ◽  
Yan Zhu ◽  
Pei Lu ◽  
Lipeng Feng ◽  
Shiyun Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mycobacterium Tuberculosis ◽  
Rna Polymerase ◽  
Essential Role ◽  
Β Subunit ◽  
Content Type ◽  
E Coli ◽  
Core Enzyme ◽  
Loop Region

ABSTRACT The ω subunit is the smallest subunit of bacterial RNA polymerase (RNAP). Although homologs of ω are essential in both eukaryotes and archaea, this subunit has been known to be dispensable for RNAP in Escherichia coli and in other bacteria. In this study, we characterized an indispensable role of the ω subunit in Mycobacterium tuberculosis . Unlike the well-studied E. coli RNAP, the M. tuberculosis RNAP core enzyme cannot be functionally assembled in the absence of the ω subunit. Importantly, substitution of M. tuberculosis ω with ω subunits from E. coli or Thermus thermophilus cannot restore the assembly of M. tuberculosis RNAP. Furthermore, by replacing different regions in M. tuberculosis ω with the corresponding regions from E. coli ω, we found a nonconserved loop region in M. tuberculosis ω essential for its function in RNAP assembly. From RNAP structures, we noticed that the location of the C-terminal region of the β′ subunit (β′CTD) in M. tuberculosis RNAP but not in E. coli or T. thermophilus RNAP is close to the ω loop region. Deletion of this β′CTD in M. tuberculosis RNAP destabilized the binding of M. tuberculosis ω on RNAP and compromised M. tuberculosis core assembly, suggesting that these two regions may function together to play a role in ω-dependent RNAP assembly in M. tuberculosis . Sequence alignment of the ω loop and the β′CTD regions suggests that the essential role of ω is probably restricted to mycobacteria. Together, our study characterized an essential role of M. tuberculosis ω and highlighted the importance of the ω loop region in M. tuberculosis RNAP assembly. IMPORTANCE DNA-dependent RNA polymerase (RNAP), which consists of a multisubunit core enzyme (α 2 ββ′ω) and a dissociable σ subunit, is the only enzyme in charge of transcription in bacteria. As the smallest subunit, the roles of ω remain the least well studied. In Escherichia coli and some other bacteria, the ω subunit is known to be nonessential for RNAP. In this study, we revealed an essential role of the ω subunit for RNAP assembly in the human pathogen Mycobacterium tuberculosis , and a mycobacterium-specific ω loop that plays a role in this function was also characterized. Our study provides fresh insights for further characterizing the roles of bacterial ω subunit.

scholarly journals Synthesis of three major auxins from glucose in EngineeredEscherichia coli

2018 ◽  
Author(s):  
Daoyi Guo ◽  
Lihua Zhang ◽  
Sijia Kong ◽  
Zhijie Liu ◽  
Xu Chu ◽  
...  
Keyword(s):  
Plant Growth ◽  
Phenylacetic Acid ◽  
De Novo ◽  
Shikimate Pathway ◽  
Aromatic Amino Acids ◽  
Plant Growth And Development ◽  
E Coli ◽  
Naturally Occurring ◽  
Hydroxyphenylacetic Acid ◽  
Indole 3 Acetic Acid

ABSTRACTIndole-3-acetic acid (IAA) is considered the most common and important naturally occurring auxin in plants and a major regulator of plant growth and development. In addition, phenylacetic acid (PAA) and 4-hydroxyphenylacetic acid (4HPA) can also play a role as auxin in some plants. In recent years, several microbes have been metabolically engineered to produce IAA from L-tryptophan. In this study, we showed that aminotransferasearo8and decarboxylasekdcfromSaccharomyces cerevisiae, and aldehyde dehydrogenasealdHfromEscherichia colihave broad substrate ranges and can catalyze the conversion of three kinds of aromatic amino acids (L-tryptophan, L-tyrosine or L-phenylalanine) to the corresponding IAA, 4HPA and PAA. Subsequently, three de novo biosynthetic pathways for the production of IAA, PAA and 4HPA from glucose were constructed inE. colithrough strengthening the shikimate pathway. This study described here shows the way for the development of agricultural microorganism for biosynthesis of plant auxin and promoting plant growth in the future.

scholarly journals Metabolic dependency of chorismate in Plasmodium falciparum suggests an alternative source for the ubiquinone biosynthesis precursor

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ana Lisa Valenciano ◽  
Maria L. Fernández-Murga ◽  
Emilio F. Merino ◽  
Nicole R. Holderman ◽  
Grant J. Butschek ◽  
...  
Keyword(s):  
Malaria Parasite ◽  
Shikimate Pathway ◽  
Aromatic Amino Acids ◽  
Defined Medium ◽  
Current Evidence ◽  
Head Group ◽  
Main Role ◽  
Alternative Source ◽  
Folate Biosynthesis

Abstract The shikimate pathway, a metabolic pathway absent in humans, is responsible for the production of chorismate, a branch point metabolite. In the malaria parasite, chorismate is postulated to be a direct precursor in the synthesis of p-aminobenzoic acid (folate biosynthesis), p-hydroxybenzoic acid (ubiquinone biosynthesis), menaquinone, and aromatic amino acids. While the potential value of the shikimate pathway as a drug target is debatable, the metabolic dependency of chorismate in P. falciparum remains unclear. Current evidence suggests that the main role of chorismate is folate biosynthesis despite ubiquinone biosynthesis being active and essential in the malaria parasite. Our goal in the present work was to expand our knowledge of the ubiquinone head group biosynthesis and its potential metabolic dependency on chorismate in P. falciparum. We systematically assessed the development of both asexual and sexual stages of P. falciparum in a defined medium in the absence of an exogenous supply of chorismate end-products and present biochemical evidence suggesting that the benzoquinone ring of ubiquinones in this parasite may be synthesized through a yet unidentified route.

scholarly journals TLR5 mediated Reactivation of Quiescent Ranavirus FV3 in Xenopus peritoneal macrophages

2021 ◽  
Author(s):  
Mrinal Samanta ◽  
Jinyeong Yim ◽  
Francisco De Jesús Andino ◽  
Matthieu Paiola ◽  
Jacques Robert
Keyword(s):  
Xenopus Laevis ◽  
Bacterial Infections ◽  
Critical Role ◽  
Disease Outbreaks ◽  
Peritoneal Macrophages ◽  
Quiescent State ◽  
E Coli ◽  
Deadly Disease

Ranaviruses such as Frog virus 3 (FV3) are large dsDNA viruses causing emerging infectious diseases leading to extensive morbidity and mortality of amphibians and other ectothermic vertebrates worldwide. Among the hosts of FV3, some are highly susceptible, whereas others are resistant and asymptomatic carriers that can take part in disseminating the infectious virus. To date, the mechanisms involved in the processes of FV3 viral persistence associate with subclinical infection transition to lethal outbreaks remain unknown. Investigation in Xenopus laevis has revealed that in the asymptomatic FV3 carrier animals, inflammation induced by heat-killed (HK) E. coli stimulation can provoke the relapse of active infection. Since Toll-like receptors (TLRs) are critical for recognizing microbial molecular patterns, we investigated their possible involvement in inflammation-induced FV3 reactivation. Among the 10 different TLRs screened for changes in expression levels following FV3 infection and HK E. coli stimulation, only TLR5 and TLR22 that both recognize bacterial products showed differential expression, and only the TLR5 ligand, flagellin, was able to induce FV3 reactivation similar to HK E. coli. Furthermore, only the TLR5 ligand flagellin induced FV3 reactivation in peritoneal macrophages both in vitro and in vivo. These data indicate that the TLR5-signalling pathway can trigger FV3 reactivation, and suggests a role of secondary bacterial infections or microbiome alterations (stress, pollution) in initiating sudden deadly disease outbreaks in amphibian populations with detectable persistent asymptomatic ranavirus. Importance This study in the amphibian Xenopus laevis provides new evidence of the critical role of macrophages in the persistence of ranaviruses in a quiescent state as well as in the reactivation of these pathogens into a virulent infection. Among the multiple microbial sensors expressed by macrophages, our data underscore the preponderant involvement of TLR5 stimulation in triggering reactivation of quiescent FV3 in resident peritoneal macrophages, unveiling a mechanistic connection between reactivation of persisting ranavirus infection and bacterial co-infection. This suggests a role for secondary bacterial infections or microbiome alterations (stress, pollution) in initiating sudden deadly disease outbreaks in amphibian populations with detectable persistent asymptomatic ranavirus.

scholarly journals Enhanced Protocatechuic Acid Production From Glucose Using Pseudomonas putida 3-Dehydroshikimate Dehydratase Expressed in a Phenylalanine-Overproducing Mutant of Escherichia coli

2021 ◽  
Vol 9 ◽  
Author(s):  
Oliver Englund Örn ◽  
Stefano Sacchetto ◽  
Ed W. J. van Niel ◽  
Rajni Hatti-Kaul
Keyword(s):  
Escherichia Coli ◽  
Protocatechuic Acid ◽  
Feedback Inhibition ◽  
Critical Concentration ◽  
Membrane Damage ◽  
Shikimate Pathway ◽  
Aromatic Amino Acids ◽  
Building Blocks ◽  
Muconic Acid ◽  
Batch Mode

Protocatechuic acid (PCA) is a strong antioxidant and is also a potential platform for polymer building blocks like vanillic acid, vanillin, muconic acid, and adipic acid. This report presents a study on PCA production from glucose via the shikimate pathway precursor 3-dehydroshikimate by heterologous expression of a gene encoding 3-dehydroshikimate dehydratase in Escherichia coli. The phenylalanine overproducing E. coli strain, engineered to relieve the allosteric inhibition of 3-deoxy-7-phosphoheptulonate synthase by the aromatic amino acids, was shown to give a higher yield of PCA than the unmodified strain under aerobic conditions. Highest PCA yield of 18 mol% per mol glucose and concentration of 4.2 g/L was obtained at a productivity of 0.079 g/L/h during cultivation in fed-batch mode using a feed of glucose and ammonium salt. Acetate was formed as a major side-product indicating a shift to catabolic metabolism as a result of feedback inhibition of the enzymes including 3-dehydroshikimate dehydratase by PCA when reaching a critical concentration. Indirect measurement of proton motive force by flow cytometry revealed no membrane damage of the cells by PCA, which was thus ruled out as a cause for affecting PCA formation.

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