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Zou Z, Robinson JI, Steinberg LK, Henderson JP. Uropathogenic Escherichia coli wield enterobactin-derived catabolites as siderophores. J Biol Chem 2024; 300:105554. [PMID: 38072063 PMCID: PMC10788543 DOI: 10.1016/j.jbc.2023.105554] [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: 07/28/2023] [Revised: 11/20/2023] [Accepted: 12/05/2023] [Indexed: 12/19/2023] Open
Abstract
Uropathogenic Escherichia coli (UPEC) secrete multiple siderophore types to scavenge extracellular iron(III) ions during clinical urinary tract infections, despite the metabolic costs of biosynthesis. Here, we find the siderophore enterobactin (Ent) and its related products to be prominent components of the iron-responsive extracellular metabolome of a model UPEC strain. Using defined Ent biosynthesis and import mutants, we identify lower molecular weight dimeric exometabolites as products of incomplete siderophore catabolism, rather than prematurely released biosynthetic intermediates. In E. coli, iron acquisition from iron(III)-Ent complexes requires intracellular esterases that hydrolyze the siderophore. Although UPEC are equipped to consume the products of completely hydrolyzed Ent, we find that Ent and its derivatives may be incompletely hydrolyzed to yield products with retained siderophore activity. These results are consistent with catabolic inefficiency as means to obtain more than one iron ion per siderophore molecule. This is compatible with an evolved UPEC strategy to maximize the nutritional returns from metabolic investments in siderophore biosynthesis.
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Affiliation(s)
- Zongsen Zou
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St Louis, Missouri, USA; Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, Missouri, USA
| | - John I Robinson
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St Louis, Missouri, USA; Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, Missouri, USA
| | - Lindsey K Steinberg
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St Louis, Missouri, USA; Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, Missouri, USA
| | - Jeffrey P Henderson
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St Louis, Missouri, USA; Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, Missouri, USA.
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2
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Zou Z, Robinson JI, Steinberg LK, Henderson JP. Uropathogenic Escherichia coli wield enterobactin-derived catabolites as siderophores. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550588. [PMID: 37546885 PMCID: PMC10402112 DOI: 10.1101/2023.07.25.550588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Uropathogenic E. coli (UPEC) secrete multiple siderophore types to scavenge extracellular iron(III) ions during clinical urinary tract infections, despite the metabolic costs of biosynthesis. Here we find the siderophore enterobactin and its related products to be prominent components of the iron-responsive extracellular metabolome of a model UPEC strain. Using defined enterobactin biosynthesis and import mutants, we identify lower molecular weight, dimeric exometabolites as products of incomplete siderophore catabolism, rather than prematurely released biosynthetic intermediates. In E. coli, iron acquisition from iron(III)-enterobactin complexes requires intracellular esterases that hydrolyze the siderophore. Although UPEC are equipped to consume the products of completely hydrolyzed enterobactin, we find that enterobactin and its derivatives may be incompletely hydrolyzed to yield products with retained siderophore activity. These results are consistent with catabolic inefficiency as means to obtain more than one iron ion per siderophore molecule. This is compatible with an evolved UPEC strategy to maximize the nutritional returns from metabolic investments in siderophore biosynthesis.
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Affiliation(s)
- Zongsen Zou
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - John I. Robinson
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Lindsey K. Steinberg
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jeffrey P. Henderson
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
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3
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Liu Z, Huang T, Shi Q, Deng Z, Lin S. Catechol siderophores framed on 2,3-dihydroxybenzoyl-L-serine from Streptomyces varsoviensis. Front Microbiol 2023; 14:1182449. [PMID: 37206338 PMCID: PMC10188961 DOI: 10.3389/fmicb.2023.1182449] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 04/10/2023] [Indexed: 05/21/2023] Open
Abstract
Enterobactin is an archetypical catecholate siderophore that plays a key role in the acquisition of ferric iron by microorganisms. Catechol moieties have been shown to be promising siderophore cores. Variants of the conserved 2,3-dihydroxybenzoate (DHB) moiety with structural modifications expand the bioactivity. Streptomyces are characterized by metabolites with diverse structures. The genomic sequence of Streptomyces varsoviensis indicated that it possessed a biosynthetic gene cluster for DHB containing siderophores and metabolic profiling revealed metabolites correlated with catechol-type natural products. Here, we report the discovery of a series of catecholate siderophores produced by S. varsoviensis and a scale-up fermentation was performed to purify these compounds for structural elucidation. A biosynthetic route for the catecholate siderophores is also proposed. These new structural features enrich the structural diversity of the enterobactin family compounds. One of the new linear enterobactin congeners shows moderate activity against a food-borne pathogen Listeria monocytogenes. This work demonstrated that changing culture conditions is still a promising approach to explore unexplored chemical diversity. The availability of the biosynthetic machinery will enrich the genetic toolbox of catechol siderophores and facilitate such engineering efforts.
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Affiliation(s)
- Zhixiang Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tingting Huang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Haihe Laboratory of Synthetic Biology, Tianjin, China
| | - Qing Shi
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Haihe Laboratory of Synthetic Biology, Tianjin, China
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Haihe Laboratory of Synthetic Biology, Tianjin, China
- Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, China
- *Correspondence: Shuangjun Lin,
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4
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Yu Y, Wang J, Liu J, Ling D, Xia J. Functional assembly of protein fragments induced by spatial confinement. PLoS One 2015; 10:e0122101. [PMID: 25875003 PMCID: PMC4398348 DOI: 10.1371/journal.pone.0122101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/17/2015] [Indexed: 02/05/2023] Open
Abstract
Natural proteins are often confined within their local microenvironments, such as three-dimensional confinement in organelles or two-dimensional confinement in lipid rafts on cytoplasmic membrane. Spatial confinement restricts proteins' entropic freedom, forces their lateral interaction, and induces new properties that the same proteins lack at the soluble state. So far, the phenomenon of environment-induced protein functional alteration still lacks a full illustration. We demonstrate here that engineered protein fragments, although being non-functional in solution, can be re-assembled within the nanometer space to give the full activity of the whole protein. Specific interaction between hexahistidine-tag (His-tag) and NiO surface immobilizes protein fragments on NiO nanoparticles to form a self-assembled protein "corona" on the particles inside the nanopores of mesoporous silica. Site-specific assembly forces a shoulder-by-shoulder orientation and promotes fragment-fragment interaction; this interaction together with spatial confinement of the mesopores results in functional re-assembly of the protein half fragments. To our surprise, a single half fragment of luciferase (non-catalytic in solution) exhibited luciferase activity when immobilized on NiO in the mesopores, in the absence of the complimentary half. This shows for the first time that spatial confinement can induce the folding of a half fragment, reconstitute the enzyme active site, and re-gain the catalytic capability of the whole protein. Our work thereby highlights the under-documented notion that aside from the chemical composition such as primary sequence, physical environment of a protein also determines its function.
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Affiliation(s)
- Yongsheng Yu
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Jianpeng Wang
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Jiahui Liu
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Daishun Ling
- Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Jiang Xia
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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5
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What macromolecular crowding can do to a protein. Int J Mol Sci 2014; 15:23090-140. [PMID: 25514413 PMCID: PMC4284756 DOI: 10.3390/ijms151223090] [Citation(s) in RCA: 355] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/04/2014] [Accepted: 12/05/2014] [Indexed: 01/17/2023] Open
Abstract
The intracellular environment represents an extremely crowded milieu, with a limited amount of free water and an almost complete lack of unoccupied space. Obviously, slightly salted aqueous solutions containing low concentrations of a biomolecule of interest are too simplistic to mimic the “real life” situation, where the biomolecule of interest scrambles and wades through the tightly packed crowd. In laboratory practice, such macromolecular crowding is typically mimicked by concentrated solutions of various polymers that serve as model “crowding agents”. Studies under these conditions revealed that macromolecular crowding might affect protein structure, folding, shape, conformational stability, binding of small molecules, enzymatic activity, protein-protein interactions, protein-nucleic acid interactions, and pathological aggregation. The goal of this review is to systematically analyze currently available experimental data on the variety of effects of macromolecular crowding on a protein molecule. The review covers more than 320 papers and therefore represents one of the most comprehensive compendia of the current knowledge in this exciting area.
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6
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Song H, Sung HP, Tse YS, Jiang M, Guo Z. Ligand-dependent active-site closure revealed in the crystal structure of Mycobacterium tuberculosis MenB complexed with product analogues. ACTA ACUST UNITED AC 2014; 70:2959-69. [PMID: 25372686 DOI: 10.1107/s1399004714019440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 08/27/2014] [Indexed: 12/23/2022]
Abstract
1,4-Dihydroxy-2-naphthoyl coenzyme A (DHNA-CoA) synthase catalyzes an essential intramolecular Claisen condensation in menaquinone biosynthesis and is an important target for the development of new antibiotics. This enzyme in Mycobacterium tuberculosis is cofactor-free and is classified as a type II DHNA-CoA synthase, differing from type I enzymes, which rely on exogenous bicarbonate for catalysis. Its crystal structures in complex with product analogues have been determined at high resolution to reveal ligand-dependent structural changes, which include the ordering of a 27-residue active-site loop (amino acids 107-133) and the reorientation of the carboxy-terminal helix (amino acids 289-301) that forms part of the active site from the opposing subunit across the trimer-trimer interface. These structural changes result in closure of the active site to the bulk solution, which is likely to take place through an induced-fit mechanism, similar to that observed for type I DHNA-CoA synthases. These findings demonstrate that the ligand-dependent conformational changes are a conserved feature of all DHNA-CoA synthases, providing new insights into the catalytic mechanism of this essential tubercular enzyme.
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Affiliation(s)
- Haigang Song
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China
| | - Hoi Pang Sung
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China
| | - Yuk Sing Tse
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China
| | - Ming Jiang
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China
| | - Zhihong Guo
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China
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7
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Sun Y, Yin S, Feng Y, Li J, Zhou J, Liu C, Zhu G, Guo Z. Molecular basis of the general base catalysis of an α/β-hydrolase catalytic triad. J Biol Chem 2014; 289:15867-79. [PMID: 24737327 DOI: 10.1074/jbc.m113.535641] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serine-histidine-aspartate triad is well known for its covalent, nucleophilic catalysis in a diverse array of enzymatic transformations. Here we show that its nucleophilicity is shielded and its catalytic role is limited to being a specific general base by an open-closed conformational change in the catalysis of (1R,6R)-2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase (or MenH), a typical α/β-hydrolase fold enzyme in the vitamin K biosynthetic pathway. This enzyme is found to adopt an open conformation without a functional triad in its ligand-free form and a closed conformation with a fully functional catalytic triad in the presence of its reaction product. The open-to-closed conformational transition involves movement of half of the α-helical cap domain, which causes extensive structural changes in the α/β-domain and forces the side chain of the triad histidine to adopt an energetically disfavored gauche conformation to form the functional triad. NMR analysis shows that the inactive open conformation without a triad prevails in ligand-free solution and is converted to the closed conformation with a properly formed triad by the reaction product. Mutation of the residues crucial to this open-closed transition either greatly decreases or completely eliminates the enzyme activity, supporting an important catalytic role for the structural change. These findings suggest that the open-closed conformational change tightly couples formation of the catalytic triad to substrate binding to enhance the substrate specificities and simultaneously shield the nucleophilicity of the triad, thus allowing it to expand its catalytic power beyond the nucleophilic catalysis.
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Affiliation(s)
- Yueru Sun
- From the Department of Chemistry, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (SAR), China and
| | - Shuhui Yin
- From the Department of Chemistry, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (SAR), China and
| | - Yitao Feng
- From the Department of Chemistry, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (SAR), China and
| | - Jie Li
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Jiahai Zhou
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Changdong Liu
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (SAR), China and Division of Life Sciences, and
| | - Guang Zhu
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (SAR), China and Division of Life Sciences, and
| | - Zhihong Guo
- From the Department of Chemistry, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region (SAR), China and
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8
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Sun Y, Song H, Li J, Li Y, Jiang M, Zhou J, Guo Z. Structural basis of the induced-fit mechanism of 1,4-dihydroxy-2-naphthoyl coenzyme A synthase from the crotonase fold superfamily. PLoS One 2013; 8:e63095. [PMID: 23658663 PMCID: PMC3637252 DOI: 10.1371/journal.pone.0063095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 03/28/2013] [Indexed: 01/25/2023] Open
Abstract
1, 4-Dihydroxy-2-naphthoyl coenzyme A (DHNA-CoA) synthase is a typical crotonase fold enzyme with an implicated role of conformational changes in catalysis. We have identified these conformational changes by determining the structures of its Escherichia coli and Synechocystis sp. PCC6803 orthologues in complex with a product analog. The structural changes include the folding of an active-site loop into a β-hairpin and significant reorientation of a helix at the carboxy terminus. Interestingly, a new interface is formed between the ordered loop and the reoriented helix, both of which also form additional interactions with the coenzyme A moiety of the ligand. Site-directed mutation of the amino acid residues involved in these ligand-induced interactions significantly diminishes the enzyme activity. These results suggest a catalytically essential induced-fit that is likely initiated by the enzyme-ligand interactions at the active site.
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Affiliation(s)
- Yueru Sun
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Haigang Song
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Jie Li
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Yan Li
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Ming Jiang
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Jiahai Zhou
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- * E-mail: (ZG); (JZ)
| | - Zhihong Guo
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- * E-mail: (ZG); (JZ)
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9
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The thiamine-dependent enzyme of the vitamin K biosynthesis catalyzes reductive C-N bond ligation between nitroarenes and α-ketoacids. Sci China Chem 2012. [DOI: 10.1007/s11426-012-4792-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Song H, Guo Z. Characterization of 1,4-dihydroxy-2-naphthoyl-coenzyme A synthase (MenB) in phylloquinone biosynthesis of Synechocystis sp. PCC 6803. Sci China Chem 2011. [DOI: 10.1007/s11426-011-4448-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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11
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Chen M, Jiang M, Sun Y, Guo ZF, Guo Z. Stabilization of the second oxyanion intermediate by 1,4-dihydroxy-2-naphthoyl-coenzyme A synthase of the menaquinone pathway: spectroscopic evidence of the involvement of a conserved aspartic acid. Biochemistry 2011; 50:5893-904. [PMID: 21627110 DOI: 10.1021/bi200376x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1,4-Dihydroxy-2-naphthoyl-coenzyme A (DHNA-CoA) synthase, or MenB, catalyzes an intramolecular Claisen condensation involving two oxyanion intermediates in the biosynthetic pathway of menaquinone, an essential respiration electron transporter in many microorganisms. Here we report the finding that the DHNA-CoA product and its analogues bind and inhibit the synthase from Escherichia coli with significant ultraviolet--visible spectral changes, which are similar to the changes induced by deprotonation of the free inhibitors in a basic solution. Dissection of the structure--affinity relationships of the inhibitors identifies the hydroxyl groups at positions 1 (C1-OH) and 4 (C4-OH) of DHNA-CoA or their equivalents as the dominant and minor sites, respectively, for the enzyme--ligand interaction that polarizes or deprotonates the bound ligands to cause the observed spectral changes. In the meantime, spectroscopic studies with active site mutants indicate that C4-OH of the enzyme-bound DHNA-CoA interacts with conserved polar residues Arg-91, Tyr-97, and Tyr-258 likely through a hydrogen bonding network that also includes Ser-161. In addition, site-directed mutation of the conserved Asp-163 to alanine causes a complete loss of the ligand binding ability of the protein, suggesting that the Asp-163 side chain is most likely hydrogen-bonded to C1-OH of DHNA-CoA to provide the dominant polarizing effect. Moreover, this mutation also completely eliminates the enzyme activity, strongly supporting the possibility that the Asp-163 side chain provides a strong stabilizing hydrogen bond to the tetrahedral oxyanion, which takes a position similar to that of C1-OH of the enzyme-bound DHNA-CoA and is the second high-energy intermediate in the intracellular Claisen condensation reaction. Interestingly, both Arg-91 and Tyr-97 are located in a disordered loop forming part of the active site of all available DHNA-CoA synthase structures. Their involvement in the interaction with the small molecule ligands suggests that the disordered loop is folded in interaction with the substrates or reaction intermediates, supporting an induced-fit catalytic mechanism for the enzyme.
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Affiliation(s)
- Minjiao Chen
- Department of Chemistry and State Key Laboratory for Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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12
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Guo ZF, Jiang M, Zheng S, Guo Z. Structural change of the enterobactin synthetase in crowded solution and its relation to crowding-enhanced product specificity in nonribosomal enterobactin biosynthesis. Bioorg Med Chem Lett 2010; 20:3855-8. [DOI: 10.1016/j.bmcl.2010.05.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 05/11/2010] [Accepted: 05/13/2010] [Indexed: 11/29/2022]
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13
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Guo ZF, Sun Y, Zheng S, Guo Z. Preferential hydrolysis of aberrant intermediates by the type II thioesterase in Escherichia coli nonribosomal enterobactin synthesis: substrate specificities and mutagenic studies on the active-site residues. Biochemistry 2010; 48:1712-22. [PMID: 19193103 DOI: 10.1021/bi802165x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The type II thioesterase EntH is a hotdog fold protein required for optimal nonribosomal biosynthesis of enterobactin in Escherichia coli. Its proposed proofreading activity in the biosynthesis is confirmed by its efficient restoration of enterobactin synthesis blocked in vitro by analogs of the cognate precursor 2,3-dihydroxybenzoate. Steady-state kinetic studies show that EntH recognizes the phosphopantetheine group and the pattern of hydroxylation in the aryl moiety of its thioester substrates. Remarkably, it is able to distinguish aberrant intermediates from the normal one in the enterobactin assembly line by demonstrating at least 10-fold higher catalytic efficiency toward thioesters derived from aberrant aryl precursors without a para-hydroxyl group, such as salicylate. By structural comparison and site-directed mutagenesis, the thioesterase is found to possess an active site closely resembling that of the 4-hydroxybenzoyl-CoA thioesterase from Arthrobacter sp. strain SU and to involve an acidic residue (glutamate-63) as the catalytic base or nucleophile like all other hotdog thioesterases. In addition, the EntH specificities toward the substrate hydroxylation pattern are found to depend on the active-site histidine-54, threonine-64, serine-67, and methionine-68 with the selectivity significantly reduced or even reversed when they are individually replaced by alanine. These residues are likely responsible for differential interaction of the enzyme with the substrates which leads to distinction between the normal and aberrant precursors in the enterobactin assembly line. These results show that the type II thioesterase evolves its distinctive ability to recognize the aberrant intermediates from the versatile catalytic platform of hotdog proteins and suggests an active search mechanism for type II thioesterases in nonribosomal peptide synthesis.
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Affiliation(s)
- Zu-Feng Guo
- Department of Chemistry, Center for Cancer Research, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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14
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Henderson JP, Crowley JR, Pinkner JS, Walker JN, Tsukayama P, Stamm WE, Hooton TM, Hultgren SJ. Quantitative metabolomics reveals an epigenetic blueprint for iron acquisition in uropathogenic Escherichia coli. PLoS Pathog 2009; 5:e1000305. [PMID: 19229321 PMCID: PMC2637984 DOI: 10.1371/journal.ppat.1000305] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 01/20/2009] [Indexed: 11/19/2022] Open
Abstract
Bacterial pathogens are frequently distinguished by the presence of acquired genes associated with iron acquisition. The presence of specific siderophore receptor genes, however, does not reliably predict activity of the complex protein assemblies involved in synthesis and transport of these secondary metabolites. Here, we have developed a novel quantitative metabolomic approach based on stable isotope dilution to compare the complement of siderophores produced by Escherichia coli strains associated with intestinal colonization or urinary tract disease. Because uropathogenic E. coli are believed to reside in the gut microbiome prior to infection, we compared siderophore production between urinary and rectal isolates within individual patients with recurrent UTI. While all strains produced enterobactin, strong preferential expression of the siderophores yersiniabactin and salmochelin was observed among urinary strains. Conventional PCR genotyping of siderophore receptors was often insensitive to these differences. A linearized enterobactin siderophore was also identified as a product of strains with an active salmochelin gene cluster. These findings argue that qualitative and quantitative epi-genetic optimization occurs in the E. coli secondary metabolome among human uropathogens. Because the virulence-associated biosynthetic pathways are distinct from those associated with rectal colonization, these results suggest strategies for virulence-targeted therapies. Urinary tract infections (UTIs) are among the most common bacterial infections treated by physicians worldwide. Although symptoms of acute infection are often resolved with a course of antibiotics, the same bacterial strain often causes subsequent bouts of symptomatic infection. Escherichia coli are the most common bacteria causing UTI and the infecting strains are widely believed to originate from the gastrointestinal tract where multiple E. coli strains reside. Here, we use a novel mass spectrometric technique in a population of patients with recurrent UTI to identify how strains that cause UTI differ from other strains that were present in the gastrointestinal tract at the same time. We found that urinary E. coli strains preferentially expressed two small molecules called yersiniabactin and salmochelin. These molecules are called siderophores, meaning they are able to scavenge iron to support bacterial survival and growth. Synthesis and transport of these small molecules requires a coordinated network of proteins encoded by a collection of different genes. These findings suggest that new antibiotics directed against yersiniabactin or salmochelin-producing E. coli strains may be an improved, and more targeted, strategy to prevent recurrent UTIs.
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Affiliation(s)
- Jeffrey P. Henderson
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jan R. Crowley
- Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jerome S. Pinkner
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jennifer N. Walker
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Pablo Tsukayama
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Walter E. Stamm
- Department of Internal Medicine, University of Washington, Seattle, Washington, United States of America
| | - Thomas M. Hooton
- Department of Internal Medicine, University of Miami, Miami, Florida, United States of America
| | - Scott J. Hultgren
- Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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