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Rezayatmand H, Golestani N, Haghighat Hoseini AS, Mousavialmaleki E, Alem M, Farzane Yegane D. Gene expression profile of Campylobacter jejuni in response to macrolide antibiotics. Arch Microbiol 2024; 206:117. [PMID: 38393387 DOI: 10.1007/s00203-024-03849-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 01/06/2024] [Accepted: 01/16/2024] [Indexed: 02/25/2024]
Abstract
Campylobacter jejuni is a foodborne pathogen that causes gastroenteritis in humans and has developed resistance to various antibiotics. The primary objective of this research was to examine the network of antibiotic resistance in C. jejuni. The study involved the wild and antibiotic-resistant strains placed in the presence and absence of antibiotics to review their gene expression profiles in response to ciprofloxacin via microarray. Differentially expressed genes (DEGs) analysis and Protein-Protein Interaction (PPI) Network studies were performed for these genes. The results showed that the resistance network of C. jejuni is modular, with different genes involved in bacterial motility, capsule synthesis, efflux, and amino acid and sugar synthesis. Antibiotic treatment resulted in the down-regulation of cluster genes related to translation, flagellum formation, and chemotaxis. In contrast, cluster genes involved in homeostasis, capsule formation, and cation efflux were up-regulated. The study also found that macrolide antibiotics inhibit the progression of C. jejuni infection by inactivating topoisomerase enzymes and increasing the activity of epimerase enzymes, trying to compensate for the effect of DNA twisting. Then, the bacterium limits the movement to conserve energy. Identifying the antibiotic resistance network in C. jejuni can aid in developing drugs to combat these bacteria. Genes involved in cell division, capsule formation, and substance transport may be potential targets for inhibitory drugs. Future research must be directed toward comprehending the underlying mechanisms contributing to the modularity of antibiotic resistance and developing strategies to disrupt and mitigate the growing threat of antibiotic resistance effectively.
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Affiliation(s)
- Hamed Rezayatmand
- Department of Pharmacy and Technology of Organic Substances, Industrial Pharmacy, Ukrainian State Chemical Technology University, Dnipro, Ukraine
| | - Nafiseh Golestani
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | | | - Elaheh Mousavialmaleki
- Pharmaceutical Science Research Center, Medicinal Chemistry Department, Faculty of Pharmacy, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Mahsa Alem
- Department of Microbiology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
| | - Donya Farzane Yegane
- Department of Pharmacognosy and Pharmaceutical Biotechnology, Faculty of Pharmacy, Lorestan University of Medical Sciences, Khorramabad, Iran
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Ramdass AC, Rampersad SN. Genome features of a novel hydrocarbonoclastic Chryseobacterium oranimense strain and its comparison to bacterial oil-degraders and to other C. oranimense strains. DNA Res 2023; 30:dsad025. [PMID: 37952165 PMCID: PMC10710014 DOI: 10.1093/dnares/dsad025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/29/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023] Open
Abstract
For the first time, we report the whole genome sequence of a hydrocarbonoclastic Chryseobacterium oranimense strain isolated from Trinidad and Tobago (COTT) and its genes involved in the biotransformation of hydrocarbons and xenobiotics through functional annotation. The assembly consisted of 11 contigs with 2,794 predicted protein-coding genes which included a diverse group of gene families involved in aliphatic and polycyclic hydrocarbon degradation. Comparative genomic analyses with 18 crude-oil degrading bacteria in addition to two C. oranimense strains not associated with oil were carried out. The data revealed important differences in terms of annotated genes involved in the hydrocarbon degradation process that may explain the molecular mechanisms of hydrocarbon and xenobiotic biotransformation. Notably, many gene families were expanded to explain COTT's competitive ability to manage habitat-specific stressors. Gene-based evidence of the metabolic potential of COTT supports the application of indigenous microbes for the remediation of polluted terrestrial environments and provides a genomic resource for improving our understanding of how to optimize these characteristics for more effective bioremediation.
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Affiliation(s)
- Amanda Christine Ramdass
- Biochemistry Research Lab (Rm216), Department of Life Sciences, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad and Tobago, West Indies
| | - Sephra Nalini Rampersad
- Biochemistry Research Lab (Rm216), Department of Life Sciences, Faculty of Science and Technology, The University of the West Indies, St. Augustine, Trinidad and Tobago, West Indies
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Lim YH, Foo HL, Loh TC, Mohamad R, Abdul Rahim R. Rapid Evaluation and Optimization of Medium Components Governing Tryptophan Production by Pediococcus acidilactici TP-6 Isolated from Malaysian Food via Statistical Approaches. Molecules 2020; 25:E779. [PMID: 32054138 PMCID: PMC7071007 DOI: 10.3390/molecules25040779] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/05/2022] Open
Abstract
Tryptophan is one of the most extensively used amino acids in livestock industry owing to its effectiveness in enhancing the growth performance of animals. Conventionally, the production of tryptophan relies heavily on genetically modified Escherichia coli but its pathogenicity is a great concern. Our recent study demonstrated that a lactic acid bacterium (LAB), Pediococcus acidilactici TP-6 that isolated from Malaysian food was a promising tryptophan producer. However, the tryptophan production must enhance further for viable industrial application. Hence, the current study evaluated the effects of medium components and optimized the medium composition for tryptophan production by P. acidilactici TP-6 statistically using Plackett-Burman Design, and Central Composite Design. The optimized medium containing molasses (14.06 g/L), meat extract (23.68 g/L), urea (5.56 g/L) and FeSO4 (0.024 g/L) significantly enhanced the tryptophan production by 150% as compared to the control de Man, Rogosa and Sharpe medium. The findings obtained in this study revealed that rapid evaluation and effective optimization of medium composition governing tryptophan production by P. acidilactici TP-6 were feasible via statistical approaches. Additionally, the current findings reveal the potential of utilizing LAB as a safer alternative tryptophan producer and provides insight for future exploitation of various amino acid productions by LAB.
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Affiliation(s)
- Ye Heng Lim
- Institute of Bioscience, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia; (Y.H.L.); (R.M.); (R.A.R.)
| | - Hooi Ling Foo
- Institute of Bioscience, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia; (Y.H.L.); (R.M.); (R.A.R.)
- Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia
| | - Teck Chwen Loh
- Department of Animal Science, Faculty of Agriculture, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia
- Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia
| | - Rosfarizan Mohamad
- Institute of Bioscience, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia; (Y.H.L.); (R.M.); (R.A.R.)
- Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia
- Institute of Tropical Forestry and Forest Products, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia
| | - Raha Abdul Rahim
- Institute of Bioscience, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia; (Y.H.L.); (R.M.); (R.A.R.)
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, UPM Serdang 43400, Selangor, Malaysia
- Office of Vice Chancellor, Universiti Teknikal Malaysia Melaka, Jalan Hang Tuah Jaya, Durian Tunggal 76100, Melaka, Malaysia
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Gut Microbiota Metabolite Indole Propionic Acid Targets Tryptophan Biosynthesis in Mycobacterium tuberculosis. mBio 2019; 10:mBio.02781-18. [PMID: 30914514 PMCID: PMC6437058 DOI: 10.1128/mbio.02781-18] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
New drugs against tuberculosis are urgently needed. The tryptophan (Trp) analog indole propionic acid (IPA) is the first antitubercular metabolite produced by human gut bacteria. Here, we show that this antibiotic blocks Trp synthesis, an in vivo essential biosynthetic pathway in M. tuberculosis. Intriguingly, IPA acts by decoupling a bacterial feedback regulatory mechanism: it mimics Trp as allosteric inhibitor of anthranilate synthase, thereby switching off Trp synthesis regardless of intracellular Trp levels. The identification of IPA’s target paves the way for the discovery of more potent TrpE ligands employing rational, target-based lead optimization. Indole propionic acid (IPA), produced by the gut microbiota, is active against Mycobacterium tuberculosisin vitro and in vivo. However, its mechanism of action is unknown. IPA is the deamination product of tryptophan (Trp) and thus a close structural analog of this essential aromatic amino acid. De novo Trp biosynthesis in M. tuberculosis is regulated through feedback inhibition: Trp acts as an allosteric inhibitor of anthranilate synthase TrpE, which catalyzes the first committed step in the Trp biosynthesis pathway. Hence, we hypothesized that IPA may mimic Trp as an allosteric inhibitor of TrpE and exert its antimicrobial effect by blocking synthesis of Trp at the TrpE catalytic step. To test our hypothesis, we carried out metabolic, chemical rescue, genetic, and biochemical analyses. Treatment of mycobacteria with IPA inhibited growth and reduced the intracellular level of Trp, an effect abrogated upon supplementation of Trp in the medium. Missense mutations at the allosteric Trp binding site of TrpE eliminated Trp inhibition and caused IPA resistance. In conclusion, we have shown that IPA blocks Trp biosynthesis in M. tuberculosis via inhibition of TrpE by mimicking the physiological allosteric inhibitor of this enzyme.
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Parthasarathy A, Cross PJ, Dobson RCJ, Adams LE, Savka MA, Hudson AO. A Three-Ring Circus: Metabolism of the Three Proteogenic Aromatic Amino Acids and Their Role in the Health of Plants and Animals. Front Mol Biosci 2018; 5:29. [PMID: 29682508 PMCID: PMC5897657 DOI: 10.3389/fmolb.2018.00029] [Citation(s) in RCA: 166] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 03/21/2018] [Indexed: 12/19/2022] Open
Abstract
Tyrosine, phenylalanine and tryptophan are the three aromatic amino acids (AAA) involved in protein synthesis. These amino acids and their metabolism are linked to the synthesis of a variety of secondary metabolites, a subset of which are involved in numerous anabolic pathways responsible for the synthesis of pigment compounds, plant hormones and biological polymers, to name a few. In addition, these metabolites derived from the AAA pathways mediate the transmission of nervous signals, quench reactive oxygen species in the brain, and are involved in the vast palette of animal coloration among others pathways. The AAA and metabolites derived from them also have integral roles in the health of both plants and animals. This review delineates the de novo biosynthesis of the AAA by microbes and plants, and the branching out of AAA metabolism into major secondary metabolic pathways in plants such as the phenylpropanoid pathway. Organisms that do not possess the enzymatic machinery for the de novo synthesis of AAA must obtain these primary metabolites from their diet. Therefore, the metabolism of AAA by the host animal and the resident microflora are important for the health of all animals. In addition, the AAA metabolite-mediated host-pathogen interactions in general, as well as potential beneficial and harmful AAA-derived compounds produced by gut bacteria are discussed. Apart from the AAA biosynthetic pathways in plants and microbes such as the shikimate pathway and the tryptophan pathway, this review also deals with AAA catabolism in plants, AAA degradation via the monoamine and kynurenine pathways in animals, and AAA catabolism via the 3-aryllactate and kynurenine pathways in animal-associated microbes. Emphasis will be placed on structural and functional aspects of several key AAA-related enzymes, such as shikimate synthase, chorismate mutase, anthranilate synthase, tryptophan synthase, tyrosine aminotransferase, dopachrome tautomerase, radical dehydratase, and type III CoA-transferase. The past development and current potential for interventions including the development of herbicides and antibiotics that target key enzymes in AAA-related pathways, as well as AAA-linked secondary metabolism leading to antimicrobials are also discussed.
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Affiliation(s)
- Anutthaman Parthasarathy
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - Penelope J. Cross
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Renwick C. J. Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, Australia
| | - Lily E. Adams
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - Michael A. Savka
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - André O. Hudson
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, United States
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Chowdhury A, Brinson R, Wei B, Stetler-Stevenson WG. Tissue Inhibitor of Metalloprotease-2 (TIMP-2): Bioprocess Development, Physicochemical, Biochemical, and Biological Characterization of Highly Expressed Recombinant Protein. Biochemistry 2017; 56:6423-6433. [PMID: 29140689 PMCID: PMC6322544 DOI: 10.1021/acs.biochem.7b00700] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Tissue inhibitor of metalloprotease-2 (TIMP-2) is a secreted 21 kDa multifunctional protein first described as an endogenous inhibitor of matrix metalloproteinases (MMPs) that prevents breakdown of the extracellular matrix often observed in chronic diseases. TIMP-2 diminishes the level of growth factor-mediated cell proliferation in vitro, as well as neoangiogenesis and tumor growth in vivo independent of its MMP inhibitory activity. These physiological properties make TIMP-2 an excellent candidate for further preclinical development as a biologic therapy of cancer. Here we present a straightforward bioprocessing methodology that yields >35 mg/L recombinant human TIMP-2 6XHis-tagged protein (rhTIMP-2) from suspension cultures of HEK-293-F cells. Enhanced rhTIMP-2-6XHis yields were achieved by optimization of both TIMP-2 cDNA codon sequence and cell culture conditions. Using a two-step chromatographic process, we achieved >95% purity with minimal processing losses. Purified rhTIMP-2-6XHis was free of mouse antigen contamination. Circular dichroism spectroscopy indicated a well-folded rhTIMP-2-6XHis that is highly stable and refractory to pH changes. Two-dimensional heteronuclear single-quantum coherence nuclear magnetic resonance of full length rhTIMP-2-6XHis also indicated a monodisperse, well-folded protein preparation. Purified rhTIMP-2-6XHis inhibited MMP-2 enzymatic activity in a dose-dependent fashion with an IC50 of ∼1.4 nM. Pretreatment of A549 lung cancer and JygMC(A) triple-negative breast cancer cells with rhTIMP-2-6XHis in low-nanomolar amounts inhibited EGF-induced proliferation to basal (unstimulated) levels. This study therefore not only offers a robust bioprocess methodology for rhTIMP-2 production but also characterizes critical physicochemical and biological attributes that are useful for monitoring quality control of the production process.
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Affiliation(s)
- Anandã Chowdhury
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, United States
| | - Robert Brinson
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and University of Maryland, 9600 Gudelsky Drive, Rockville, Maryland 20850, United States
| | - Beiyang Wei
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, United States
| | - William G. Stetler-Stevenson
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, United States
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Srivastava A, Sinha S. Uncoupling of an ammonia channel as a mechanism of allosteric inhibition in anthranilate synthase of Serratia marcescens: dynamic and graph theoretical analysis. MOLECULAR BIOSYSTEMS 2017; 13:142-155. [DOI: 10.1039/c6mb00646a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Network modeling and molecular dynamic studies reveal the perturbation in communication pathways as a mechanism of allosteric inhibition in anthranilate synthase.
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Affiliation(s)
- Ashutosh Srivastava
- Centre for Protein Science
- Design
- Engineering (CPSDE)
- Department of Biological Sciences
- Indian Institute of Science Education Research Mohali
| | - Somdatta Sinha
- Centre for Protein Science
- Design
- Engineering (CPSDE)
- Department of Biological Sciences
- Indian Institute of Science Education Research Mohali
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Bashiri G, Johnston JM, Evans GL, Bulloch EMM, Goldstone DC, Jirgis ENM, Kleinboelting S, Castell A, Ramsay RJ, Manos-Turvey A, Payne RJ, Lott JS, Baker EN. Structure and inhibition of subunit I of the anthranilate synthase complex of Mycobacterium tuberculosis and expression of the active complex. ACTA ACUST UNITED AC 2015; 71:2297-308. [DOI: 10.1107/s1399004715017216] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 09/14/2015] [Indexed: 01/16/2023]
Abstract
The tryptophan-biosynthesis pathway is essential for Mycobacterium tuberculosis (Mtb) to cause disease, but not all of the enzymes that catalyse this pathway in this organism have been identified. The structure and function of the enzyme complex that catalyses the first committed step in the pathway, the anthranilate synthase (AS) complex, have been analysed. It is shown that the open reading frames Rv1609 (trpE) and Rv0013 (trpG) encode the chorismate-utilizing (AS-I) and glutamine amidotransferase (AS-II) subunits of the AS complex, respectively. Biochemical assays show that when these subunits are co-expressed a bifunctional AS complex is obtained. Crystallization trials on Mtb-AS unexpectedly gave crystals containing only AS-I, presumably owing to its selective crystallization from solutions containing a mixture of the AS complex and free AS-I. The three-dimensional structure reveals that Mtb-AS-I dimerizes via an interface that has not previously been seen in AS complexes. As is the case in other bacteria, it is demonstrated that Mtb-AS shows cooperative allosteric inhibition by tryptophan, which can be rationalized based on interactions at this interface. Comparative inhibition studies on Mtb-AS-I and related enzymes highlight the potential for single inhibitory compounds to target multiple chorismate-utilizing enzymes for TB drug discovery.
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Manos-Turvey A, Cergol KM, Salam NK, Bulloch EMM, Chi G, Pang A, Britton WJ, West NP, Baker EN, Lott JS, Payne RJ. Synthesis and evaluation of M. tuberculosis salicylate synthase (MbtI) inhibitors designed to probe plasticity in the active site. Org Biomol Chem 2012; 10:9223-36. [DOI: 10.1039/c2ob26736e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Esparza M, Cárdenas JP, Bowien B, Jedlicki E, Holmes DS. Genes and pathways for CO2 fixation in the obligate, chemolithoautotrophic acidophile, Acidithiobacillus ferrooxidans, carbon fixation in A. ferrooxidans. BMC Microbiol 2010; 10:229. [PMID: 20799944 PMCID: PMC2942843 DOI: 10.1186/1471-2180-10-229] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 08/27/2010] [Indexed: 11/10/2022] Open
Abstract
Background Acidithiobacillus ferrooxidans is chemolithoautotrophic γ-proteobacterium that thrives at extremely low pH (pH 1-2). Although a substantial amount of information is available regarding CO2 uptake and fixation in a variety of facultative autotrophs, less is known about the processes in obligate autotrophs, especially those living in extremely acidic conditions, prompting the present study. Results Four gene clusters (termed cbb1-4) in the A. ferrooxidans genome are predicted to encode enzymes and structural proteins involved in carbon assimilation via the Calvin-Benson-Bassham (CBB) cycle including form I of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO, EC 4.1.1.39) and the CO2-concentrating carboxysomes. RT-PCR experiments demonstrated that each gene cluster is a single transcriptional unit and thus is an operon. Operon cbb1 is divergently transcribed from a gene, cbbR, encoding the LysR-type transcriptional regulator CbbR that has been shown in many organisms to regulate the expression of RubisCO genes. Sigma70-like -10 and -35 promoter boxes and potential CbbR-binding sites (T-N11-A/TNA-N7TNA) were predicted in the upstream regions of the four operons. Electrophoretic mobility shift assays (EMSAs) confirmed that purified CbbR is able to bind to the upstream regions of the cbb1, cbb2 and cbb3 operons, demonstrating that the predicted CbbR-binding sites are functional in vitro. However, CbbR failed to bind the upstream region of the cbb4 operon that contains cbbP, encoding phosphoribulokinase (EC 2.7.1.19). Thus, other factors not present in the assay may be required for binding or the region lacks a functional CbbR-binding site. The cbb3 operon contains genes predicted to encode anthranilate synthase components I and II, catalyzing the formation of anthranilate and pyruvate from chorismate. This suggests a novel regulatory connection between CO2 fixation and tryptophan biosynthesis. The presence of a form II RubisCO could promote the ability of A. ferrooxidans to fix CO2 at different concentrations of CO2. Conclusions A. ferrooxidans has features of cbb gene organization for CO2-assimilating functions that are characteristic of obligate chemolithoautotrophs and distinguish this group from facultative autotrophs. The most conspicuous difference is a separate operon for the cbbP gene. It is hypothesized that this organization may provide greater flexibility in the regulation of expression of genes involved in inorganic carbon assimilation.
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Affiliation(s)
- Mario Esparza
- Center for Bioinformatics and Genome Biology, MIFAB, Fundación Ciencia para la Vida and Depto. de Ciencias Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
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Webby CJ, Jiao W, Hutton RD, Blackmore NJ, Baker HM, Baker EN, Jameson GB, Parker EJ. Synergistic allostery, a sophisticated regulatory network for the control of aromatic amino acid biosynthesis in Mycobacterium tuberculosis. J Biol Chem 2010; 285:30567-76. [PMID: 20667835 DOI: 10.1074/jbc.m110.111856] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The shikimate pathway, responsible for aromatic amino acid biosynthesis, is required for the growth of Mycobacterium tuberculosis and is a potential drug target. The first reaction is catalyzed by 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAH7PS). Feedback regulation of DAH7PS activity by aromatic amino acids controls shikimate pathway flux. Whereas Mycobacterium tuberculosis DAH7PS (MtuDAH7PS) is not inhibited by the addition of Phe, Tyr, or Trp alone, combinations cause significant loss of enzyme activity. In the presence of 200 μm Phe, only 2.4 μm Trp is required to reduce enzymic activity to 50%. Reaction kinetics were analyzed in the presence of inhibitory concentrations of Trp/Phe or Trp/Tyr. In the absence of inhibitors, the enzyme follows Michaelis-Menten kinetics with respect to substrate erythrose 4-phosphate (E4P), whereas the addition of inhibitor combinations caused significant homotropic cooperativity with respect to E4P, with Hill coefficients of 3.3 (Trp/Phe) and 2.8 (Trp/Tyr). Structures of MtuDAH7PS/Trp/Phe, MtuDAH7PS/Trp, and MtuDAH7PS/Phe complexes were determined. The MtuDAH7PS/Trp/Phe homotetramer binds four Trp and six Phe molecules. Binding sites for both aromatic amino acids are formed by accessory elements to the core DAH7PS (β/α)(8) barrel that are unique to the type II DAH7PS family and contribute to the tight dimer and tetramer interfaces. A comparison of the liganded and unliganded MtuDAH7PS structures reveals changes in the interface areas associated with inhibitor binding and a small displacement of the E4P binding loop. These studies uncover a previously unrecognized mode of control for the branched pathways of aromatic amino acid biosynthesis involving synergistic inhibition by specific pairs of pathway end products.
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Affiliation(s)
- Celia J Webby
- From the Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
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