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Sadeeshkumar H, Balaji A, Sutherland AG, Mootien S, Anthony KG, Breaker RR. Screening for small molecule inhibitors of SAH nucleosidase using an SAH riboswitch. Anal Biochem 2023; 666:115047. [PMID: 36682579 DOI: 10.1016/j.ab.2023.115047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/30/2022] [Accepted: 01/09/2023] [Indexed: 01/21/2023]
Abstract
Due to the emergence of multidrug resistant pathogens, it is imperative to identify new targets for antibiotic drug discovery. The S-adenosylhomocysteine (SAH) nucleosidase enzyme is a promising target for antimicrobial drug development due to its critical functions in multiple bacterial processes including recycling of toxic byproducts of S-adenosylmethionine (SAM)-mediated reactions and producing the precursor of the universal quorum sensing signal, autoinducer-2 (AI-2). Riboswitches are structured RNA elements typically used by bacteria to precisely monitor and respond to changes in essential bacterial processes, including metabolism. Natural riboswitches fused to a reporter gene can be exploited to detect changes in metabolism or in physiological signaling. We performed a high-throughput screen (HTS) using an SAH-riboswitch controlled β-galactosidase reporter gene in Escherichia coli to discover small molecules that inhibit SAH recycling. We demonstrate that the assay strategy using SAH riboswitches to detect the effects of SAH nucleosidase inhibitors can quickly identify compounds that penetrate the barriers of Gram-negative bacterial cells and perturb pathways involving SAH.
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Affiliation(s)
- Harini Sadeeshkumar
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520-8103, USA
| | - Aparaajita Balaji
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520-8103, USA
| | | | | | - Karen G Anthony
- L2 Diagnostics, LLC, 300 George Street, New Haven, CT, 06511, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520-8103, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520-8103, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT, 06520-8103, USA.
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2
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Brown M, Zoi I, Antoniou D, Namanja-Magliano HA, Schwartz SD, Schramm VL. Inverse heavy enzyme isotope effects in methylthioadenosine nucleosidases. Proc Natl Acad Sci U S A 2021; 118:e2109118118. [PMID: 34580228 PMCID: PMC8501826 DOI: 10.1073/pnas.2109118118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2021] [Indexed: 11/18/2022] Open
Abstract
Heavy enzyme isotope effects occur in proteins substituted with 2H-, 13C-, and 15N-enriched amino acids. Mass alterations perturb femtosecond protein motions and have been used to study the linkage between fast motions and transition-state barrier crossing. Heavy enzymes typically show slower rates for their chemical steps. Heavy bacterial methylthioadenosine nucleosidases (MTANs from Helicobactor pylori and Escherichia coli) gave normal isotope effects in steady-state kinetics, with slower rates for the heavy enzymes. However, both enzymes revealed rare inverse isotope effects on their chemical steps, with faster chemical steps in the heavy enzymes. Computational transition-path sampling studies of H. pylori and E. coli MTANs indicated closer enzyme-reactant interactions in the heavy MTANs at times near the transition state, resulting in an improved reaction coordinate geometry. Specific catalytic interactions more favorable for heavy MTANs include improved contacts to the catalytic water nucleophile and to the adenine leaving group. Heavy bacterial MTANs depart from other heavy enzymes as slowed vibrational modes from the heavy isotope substitution caused improved barrier-crossing efficiency. Improved sampling frequency and reactant coordinate distances are highlighted as key factors in MTAN transition-state stabilization.
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Affiliation(s)
- Morais Brown
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Ioanna Zoi
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721
| | - Dimitri Antoniou
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721
| | | | - Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461;
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3
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Chen S, Kapilashrami K, Senevirathne C, Wang Z, Wang J, Linscott JA, Luo M. Substrate-Differentiated Transition States of SET7/9-Catalyzed Lysine Methylation. J Am Chem Soc 2019; 141:8064-8067. [PMID: 31034218 DOI: 10.1021/jacs.9b02553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Transition state stabilization is essential for rate acceleration of enzymatic reactions. Despite extensive studies on various transition state structures of enzymes, an intriguing puzzle is whether an enzyme can accommodate multiple transition states (TSs) to catalyze a chemical reaction. It is experimentally challenging to study this proposition in terms of the choices of suitable enzymes and the feasibility to distinguish multiple TSs. As a paradigm with the protein lysine methyltransferase (PKMT) SET7/9 paired with its physiological substrates H3 and p53, their TSs were solved with experimental kinetic isotope effects as computational constraints. Remarkably, SET7/9 adopts two structurally distinct TSs, a nearly symmetric SN2 and an extremely early SN2, for H3K4 and p53K372 methylation, respectively. The two TSs are also different from those previously revealed for other PKMTs. The setting of multiple TSs is expected to be essential for SET7/9 and likely other PKMTs to act on broad substrates with high efficiency.
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Affiliation(s)
| | | | | | - Zhen Wang
- Department of Biochemistry , Albert Einstein College of Medicine , Bronx , New York 10461 , United States
| | | | - Joshua A Linscott
- Program of Pharmacology, Weill Graduate School of Medical Science , Cornell University , New York , New York 10021 , United States
| | - Minkui Luo
- Program of Pharmacology, Weill Graduate School of Medical Science , Cornell University , New York , New York 10021 , United States
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4
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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5
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Kaur A, Capalash N, Sharma P. Quorum sensing in thermophiles: prevalence of autoinducer-2 system. BMC Microbiol 2018; 18:62. [PMID: 29954335 PMCID: PMC6022435 DOI: 10.1186/s12866-018-1204-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 06/19/2018] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Quorum sensing is a mechanism of cell to cell communication that requires the production and detection of signaling molecules called autoinducers. Although mesophilic bacteria is known to utilize this for synchronization of physiological processes such as bioluminescence, virulence, biofilm formation, motility and cell competency through signaling molecules (acyl homoserine lactones, AI-1; oligopeptides, peptide based system and furanosyl borate diester, AI-2), the phenomenon of quorum sensing in thermophiles is largely unknown. RESULTS In this study, proteomes of 106 thermophilic eubacteria and 21 thermophilic archaea have been investigated for the above three major quorum sensing systems to find the existence of quorum sensing in these thermophiles as there are evidences for the formation of biofilms in hot environments. Our investigation demonstrated that AI-1 system is absent in thermophiles. Further, complete peptide based two component systems for quorum sensing was also not found in any thermophile however the traces for the presence of response regulators for peptide based system were found in some of them. BLASTp search using LuxS (AI-2 synthase) protein sequence of Escherichia coli str. K-12 substr. MG1655 and autoinducer-2 receptors (LuxP of Vibrio harveyi, LsrB of E. coli str. K-12 substr. MG1655 and RbsB of Aggregatibacter actinomycetemcomitans) as queries revealed that 17 thermophilic bacteria from phyla Deinococcus- Thermus and Firmicutes possess complete AI-2 system (LuxS and LsrB and/or RbsB). Out of 106 thermophilic eubacteria 18 from phyla Deinococcus- Thermus, Proteobacteria and Firmicutes have only LuxS that might function as AI-2 synthesizing protein whereas, 16 are having only LsrB and/or RbsB which may function as AI-2 receptor in biofilms. CONCLUSIONS We anticipate that thermophilic bacteria may use elements of LsrB and RbsB operon for AI-2 signal transduction and they may use quorum sensing for purposes like biofilm formation. Nevertheless, thermophiles in which no known quorum sensing system was found may use some unknown mechanisms as the mode of communication. Further information regarding quorum sensing will be explored to develop strategies to disrupt the biofilms of thermophiles.
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Affiliation(s)
- Amandeep Kaur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Neena Capalash
- Department of Biotechnology, Panjab University, Chandigarh, India
| | - Prince Sharma
- Department of Microbiology, Panjab University, Chandigarh, India
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6
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Xu Y, Wang L, Chen J, Zhao J, Fan S, Dong Y, Ha NC, Quan C. Structural and Functional Analyses of Periplasmic 5'-Methylthioadenosine/S-Adenosylhomocysteine Nucleosidase from Aeromonas hydrophila. Biochemistry 2017; 56:5347-5355. [PMID: 28862845 DOI: 10.1021/acs.biochem.7b00691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Gram-negative, rod-shaped bacterium Aeromonas hydrophila has two multifunctional 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) enzymes, MtaN-1 and MtaN-2, that differ from those in other bacteria. These proteins are essential for several metabolic pathways, including biological methylation, polyamine biosynthesis, methionine recycling, and bacterial quorum sensing. To gain insight into how these two proteins function, we determined four high-resolution crystal structures of MtaN-1 in its apo form and in complex with the substrates S-adenosyl-l-homocysteine, 5'-methylthioadenosine, and 5'-deoxyadenosine. We found that the domain structures were generally similar, although slight differences were evident. The crystal structure demonstrates that AhMtaN-1 has an extension of the binding pocket and revealed that a tryptophan in the active site (Trp199) may play a major role in substrate binding, unlike in other MTAN proteins. Mutation of the Trp199 residue completely abolished the enzyme activity. Trp199 was identified as an active site residue that is essential for catalysis. Furthermore, biochemical characterization of AhMtaN-1 and AhMtaN-2 demonstrated that AhMtaN-1 exhibits inherent trypsin resistance that is higher than that of AhMtaN-2. Additionally, the thermally unfolded AhMtaN-2 protein is capable of refolding into active forms, whereas the thermally unfolded AhMtaN-1 protein does not have this ability. Examining the different biochemical characteristics related to the functional roles of AhMtaN-1 and AhMtaN-2 would be interesting. Indeed, the biochemical characterization of these structural features would provide a structural basis for the design of new antibiotics against A. hydrophila.
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Affiliation(s)
- Yongbin Xu
- Department of Bioengineering, College of Life Science, Dalian Minzu University , Dalian 116600, Liaoning, China.,Key Laboratory of Biotechnology and Bioresources Utilization (Dalian Minzu University) , Ministry of Education, Dalian, China
| | - Lulu Wang
- School of Life Science and Biotechnology, Dalian University of Technology , No. 2 Linggong Road, Dalian 116024, Liaoning, China
| | - Jinli Chen
- Department of Bioengineering, College of Life Science, Dalian Minzu University , Dalian 116600, Liaoning, China
| | - Jing Zhao
- Department of Bioengineering, College of Life Science, Dalian Minzu University , Dalian 116600, Liaoning, China.,Key Laboratory of Biotechnology and Bioresources Utilization (Dalian Minzu University) , Ministry of Education, Dalian, China
| | - Shengdi Fan
- Department of Bioengineering, College of Life Science, Dalian Minzu University , Dalian 116600, Liaoning, China.,Key Laboratory of Biotechnology and Bioresources Utilization (Dalian Minzu University) , Ministry of Education, Dalian, China
| | - Yuesheng Dong
- School of Life Science and Biotechnology, Dalian University of Technology , No. 2 Linggong Road, Dalian 116024, Liaoning, China
| | - Nam-Chul Ha
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University , Gwanak-gu, Seoul 151-742, Republic of Korea
| | - Chunshan Quan
- Department of Bioengineering, College of Life Science, Dalian Minzu University , Dalian 116600, Liaoning, China.,Key Laboratory of Biotechnology and Bioresources Utilization (Dalian Minzu University) , Ministry of Education, Dalian, China
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7
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Namanja-Magliano HA, Evans GB, Harijan RK, Tyler PC, Schramm VL. Transition State Analogue Inhibitors of 5'-Deoxyadenosine/5'-Methylthioadenosine Nucleosidase from Mycobacterium tuberculosis. Biochemistry 2017; 56:5090-5098. [PMID: 28836767 DOI: 10.1021/acs.biochem.7b00576] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mycobacterium tuberculosis 5'-deoxyadenosine/5'-methylthioadenosine nucleosidase (Rv0091) catalyzes the N-riboside hydrolysis of its substrates 5'-methylthioadenosine (MTA) and 5'-deoxyadenosine (5'-dAdo). 5'-dAdo is the preferred substrate, a product of radical S-adenosylmethionine-dependent enzyme reactions. Rv0091 is characterized by a ribocation-like transition state, with low N-ribosidic bond order, an N7-protonated adenine leaving group, and an activated but weakly bonded water nucleophile. DADMe-Immucillins incorporating 5'-substituents of the substrates 5'-dAdo and MTA were synthesized and characterized as inhibitors of Rv0091. 5'-Deoxy-DADMe-Immucillin-A was the most potent among the 5'-dAdo transition state analogues with a dissociation constant of 640 pM. Among the 5'-thio substituents, hexylthio-DADMe-Immucillin-A was the best inhibitor at 87 pM. The specificity of Rv0091 for the Immucillin transition state analogues differs from those of other bacterial homologues because of an altered hydrophobic tunnel accepting the 5'-substituents. Inhibitors of Rv0091 had weak cell growth effects on M. tuberculosis or Mycobacterium smegmatis but were lethal toward Helicobacter pylori, where the 5'-methylthioadenosine nucleosidase is essential in menaquinone biosynthesis. We propose that Rv0091 plays a role in 5'-deoxyadenosine recycling but is not essential for growth in these Mycobacteria.
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Affiliation(s)
- Hilda A Namanja-Magliano
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Gary B Evans
- The Ferrier Research Institute, Victoria University of Wellington , Lower Hutt, Wellington 5040, New Zealand.,The Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , Auckland, New Zealand
| | - Rajesh K Harijan
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Peter C Tyler
- The Ferrier Research Institute, Victoria University of Wellington , Lower Hutt, Wellington 5040, New Zealand
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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8
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Namanja-Magliano HA, Stratton CF, Schramm VL. Transition State Structure and Inhibition of Rv0091, a 5'-Deoxyadenosine/5'-methylthioadenosine Nucleosidase from Mycobacterium tuberculosis. ACS Chem Biol 2016; 11:1669-76. [PMID: 27019223 DOI: 10.1021/acschembio.6b00144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) is a bacterial enzyme that catalyzes the hydrolysis of the N-ribosidic bond in 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH). MTAN activity has been linked to quorum sensing pathways, polyamine biosynthesis, and adenine salvage. Previously, the coding sequence of Rv0091 was annotated as a putative MTAN in Mycobacterium tuberculosis. Rv0091 was expressed in Escherichia coli, purified to homogeneity, and shown to be a homodimer, consistent with MTANs from other microorganisms. Substrate specificity for Rv0091 gave a preference for 5'-deoxyadenosine relative to MTA or SAH. Intrinsic kinetic isotope effects (KIEs) for the hydrolysis of [1'-(3)H], [1'-(14)C], [5'-(3)H2], [9-(15)N], and [7-(15)N]MTA were determined to be 1.207, 1.038, 0.998, 1.021, and 0.998, respectively. A model for the transition state structure of Rv0091 was determined by matching KIE values predicted via quantum chemical calculations to the intrinsic KIEs. The transition state shows a substantial loss of C1'-N9 bond order, well-developed oxocarbenium character of the ribosyl ring, and weak participation of the water nucleophile. Electrostatic potential surface maps for the Rv0091 transition state structure show similarity to DADMe-immucillin transition state analogues. DADMe-immucillin transition state analogues showed strong inhibition of Rv0091, with the most potent inhibitor (5'-hexylthio-DADMe-immucillinA) displaying a Ki value of 87 pM.
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Affiliation(s)
- Hilda A. Namanja-Magliano
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
| | - Christopher F. Stratton
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
| | - Vern L. Schramm
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
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9
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Wang S, Cameron SA, Clinch K, Evans GB, Wu Z, Schramm VL, Tyler PC. New Antibiotic Candidates against Helicobacter pylori. J Am Chem Soc 2015; 137:14275-80. [PMID: 26494017 PMCID: PMC6709534 DOI: 10.1021/jacs.5b06110] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Helicobacter pylori is a Gram-negative bacterium that colonizes the gut of over 50% of the world's population. It is responsible for most peptic ulcers and is an important risk factor for gastric cancer. Antibiotic treatment for H. pylori infections is challenging as drug resistance has developed to antibiotics with traditional mechanisms of action. H. pylori uses an unusual pathway for menaquinone biosynthesis with 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) catalyzing an essential step. We validated MTAN as a target with a transition-state analogue of the enzyme [Wang, S.; Haapalainen, A. M.; Yan, F.; et al. Biochemistry 2012, 51, 6892-6894]. MTAN inhibitors will only be useful drug candidates if they can both include tight binding to the MTAN target and have the ability to penetrate the complex cell membrane found in Gram-negative H. pylori. Here we explore structural scaffolds for MTAN inhibition and for growth inhibition of cultured H. pylori. Sixteen analogues reported here are transition-state analogues of H. pylori MTAN with dissociation constants of 50 pM or below. Ten of these prevent growth of the H. pylori with IC90 values below 0.01 μg/mL. These remarkable compounds meet the criteria for potent inhibition and cell penetration. As a consequence, 10 new H. pylori antibiotic candidates are identified, all of which prevent H. pylori growth at concentrations 16-2000-fold lower than the five antibiotics, amoxicillin, metronidazole, levofloxacin, tetracyclin, and clarithromycin, commonly used to treat H. pylori infections. X-ray crystal structures of MTAN cocrystallized with several inhibitors show them to bind in the active site making interactions consistent with transition-state analogues.
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Affiliation(s)
- Shanzhi Wang
- Department of Biochemistry, Albert Einstein College of Medicine, New York, New York, 10461, United States
| | - Scott A. Cameron
- Department of Biochemistry, Albert Einstein College of Medicine, New York, New York, 10461, United States
| | - Keith Clinch
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt, Wellington 5040, New Zealand
| | - Gary B. Evans
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt, Wellington 5040, New Zealand
| | - Zhimeng Wu
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt, Wellington 5040, New Zealand
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, New York, New York, 10461, United States
| | - Peter C. Tyler
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt, Wellington 5040, New Zealand
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10
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Abstract
Cell-cell communication, or quorum sensing, is a widespread phenomenon in bacteria that is used to coordinate gene expression among local populations. Its use by bacterial pathogens to regulate genes that promote invasion, defense, and spread has been particularly well documented. With the ongoing emergence of antibiotic-resistant pathogens, there is a current need for development of alternative therapeutic strategies. An antivirulence approach by which quorum sensing is impeded has caught on as a viable means to manipulate bacterial processes, especially pathogenic traits that are harmful to human and animal health and agricultural productivity. The identification and development of chemical compounds and enzymes that facilitate quorum-sensing inhibition (QSI) by targeting signaling molecules, signal biogenesis, or signal detection are reviewed here. Overall, the evidence suggests that QSI therapy may be efficacious against some, but not necessarily all, bacterial pathogens, and several failures and ongoing concerns that may steer future studies in productive directions are discussed. Nevertheless, various QSI successes have rightfully perpetuated excitement surrounding new potential therapies, and this review highlights promising QSI leads in disrupting pathogenesis in both plants and animals.
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11
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Haapalainen AM, Thomas K, Tyler PC, Evans GB, Almo SC, Schramm VL. Salmonella enterica MTAN at 1.36 Å resolution: a structure-based design of tailored transition state analogs. Structure 2013; 21:963-74. [PMID: 23685211 DOI: 10.1016/j.str.2013.04.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 04/08/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
Abstract
Accumulation of 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH) in bacteria disrupts the S-adenosylmethionine pool to alter biological methylations, synthesis of polyamines, and production of quorum-sensing molecules. Bacterial metabolism of MTA and SAH depends on MTA/SAH nucleosidase (MTAN), an enzyme not present in humans and a target for quorum sensing because MTAN activity is essential for synthesis of autoinducer-2 molecules. Crystals of Salmonella enterica MTAN with product and transition state analogs of MTA and SAH explain the structural contacts causing pM binding affinity for the inhibitor and reveal a "water-wire" channel for the catalytic nucleophile. The crystal structure shows an extension of the binding pocket filled with polyethylene glycol. We exploited this discovery by the design and synthesis of tailored modifications of the currently existing transition state analogs to fill this site. This site was not anticipated in MTAN structures. Tailored inhibitors with dissociation constants of 5 to 15 pM are characterized.
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Affiliation(s)
- Antti M Haapalainen
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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12
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Abstract
Enzymes achieve their transition states by dynamic conformational searches on the femtosecond to picosecond time scale. Mimics of reactants at enzymatic transition states bind tightly to enzymes by stabilizing the conformation optimized through evolution for transition state formation. Instead of forming the transient transition state geometry, transition state analogues convert the short-lived transition state to a stable thermodynamic state. Enzymatic transition states are understood by combining kinetic isotope effects and computational chemistry. Analogues of the transition state can bind millions of times more tightly than substrates and show promise for drug development for several targets.
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Affiliation(s)
- Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx New York 10461, United States.
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13
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Thomas K, Haapalainen AM, Burgos ES, Evans GB, Tyler PC, Gulab S, Guan R, Schramm VL. Femtomolar inhibitors bind to 5'-methylthioadenosine nucleosidases with favorable enthalpy and entropy. Biochemistry 2012; 51:7541-50. [PMID: 22931458 DOI: 10.1021/bi3009938] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) catalyzes the hydrolytic cleavage of adenine from methylthioadenosine (MTA). Inhibitor design and synthesis informed by transition state analysis have developed femtomolar inhibitors for MTANs, among the most powerful known noncovalent enzyme inhibitors. Thermodynamic analyses of the inhibitor binding reveals a combination of highly favorable contributions from enthalpic (-24.7 to -4.0 kcal mol(-1)) and entropic (-10.0 to 6.4 kcal mol(-1)) interactions. Inhibitor binding to similar MTANs from different bacterial species gave distinct energetic contributions from similar catalytic sites. Thus, binding of four transition state analogues to EcMTAN and SeMTAN is driven primarily by enthalpy, while binding to VcMTAN is driven primarily by entropy. Human MTA phosphorylase (hMTAP) has a transition state structure closely related to that of the bacterial MTANs, and it binds tightly to some of the same transition state analogues. However, the thermodynamic signature of binding of an inhibitor to hMTAP differs completely from that with MTANs. We conclude that factors other than first-sphere catalytic residue contacts contribute to binding of inhibitors because the thermodynamic signature differs between bacterial species of the same enzyme.
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Affiliation(s)
- Keisha Thomas
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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14
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Lou M, Burger SK, Gilpin ME, Gawuga V, Capretta A, Berti PJ. Transition State Analysis of Enolpyruvylshikimate 3-Phosphate (EPSP) Synthase (AroA)-Catalyzed EPSP Hydrolysis. J Am Chem Soc 2012; 134:12958-69. [PMID: 22765279 DOI: 10.1021/ja304339h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Meiyan Lou
- Department of Chemistry & Chemical Biology, and †Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Steven K. Burger
- Department of Chemistry & Chemical Biology, and †Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Meghann E. Gilpin
- Department of Chemistry & Chemical Biology, and †Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Vivian Gawuga
- Department of Chemistry & Chemical Biology, and †Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Alfredo Capretta
- Department of Chemistry & Chemical Biology, and †Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Paul J. Berti
- Department of Chemistry & Chemical Biology, and †Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
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15
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Clinch K, Evans GB, Fröhlich RFG, Gulab SA, Gutierrez JA, Mason JM, Schramm VL, Tyler PC, Woolhouse AD. Transition state analogue inhibitors of human methylthioadenosine phosphorylase and bacterial methylthioadenosine/S-adenosylhomocysteine nucleosidase incorporating acyclic ribooxacarbenium ion mimics. Bioorg Med Chem 2012; 20:5181-7. [PMID: 22854195 DOI: 10.1016/j.bmc.2012.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 06/28/2012] [Accepted: 07/04/2012] [Indexed: 11/24/2022]
Abstract
Several acyclic hydroxy-methylthio-amines with 3-5 carbon atoms were prepared and coupled via a methylene link to 9-deazaadenine. The products were tested for inhibition against human MTAP and Escherichia coli and Neisseria meningitidis MTANs and gave K(i) values as low as 0.23 nM. These results were compared to those obtained with 1st and 2nd generation inhibitors (1S)-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino-5-methylthio-D-ribitol (MT-Immucillin-A, 3) and (3R,4S)-1-[9-deazaadenin-9-yl)methyl]3-hydroxy-4-methylthiomethylpyrrolidine (MT-DADMe-Immucillin-A, 4). The best inhibitors were found to exhibit binding affinities of approximately 2- to 4-fold those of 3 but were significantly weaker than 4. Cleavage of the 2,3 carbon-carbon bond in MT-Immucillin-A (3) gave an acyclic product (79) with a 21,500 fold loss of activity against E. coli MTAN. In another case, N-methylation of a side chain secondary amine resulted in a 250-fold loss of activity against the same enzyme [(±)-65 vs (±)-68]. The inhibition results were also contrasted with those acyclic derivatives previously prepared as inhibitors for a related enzyme, purine nucleoside phosphorylase (PNP), where some inhibitors in the latter case were found to be more potent than their cyclic counterparts.
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Affiliation(s)
- Keith Clinch
- Carbohydrate Chemistry, Industrial Research Limited, PO Box 31310, Lower Hutt 5040, New Zealand.
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16
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Griswold WR, Castro JN, Fisher AJ, Toney MD. Ground-state electronic destabilization via hyperconjugation in aspartate aminotransferase. J Am Chem Soc 2012; 134:8436-8. [PMID: 22551424 DOI: 10.1021/ja302809e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Binding isotope effects for l-aspartate reacting with the inactive K258A mutant of PLP-dependent aspartate aminotransferase to give a stable external aldimine intermediate are reported. They provide direct evidence for electronic ground-state destabilization via hyperconjugation. The smaller equilibrium isotope effect with deazaPLP-reconstituted K258A indicates that the pyridine nitrogen plays an important role in labilizing the Cα-H bond.
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Affiliation(s)
- Wait R Griswold
- Department of Chemistry, University of California - Davis, 95616, United States
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17
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Wang S, Lim J, Thomas K, Yan F, Angeletti RH, Schramm VL. A complex of methylthioadenosine/S-adenosylhomocysteine nucleosidase, transition state analogue, and nucleophilic water identified by mass spectrometry. J Am Chem Soc 2012; 134:1468-70. [PMID: 22239413 DOI: 10.1021/ja211176q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An enzyme-stabilized nucleophilic water molecule has been implicated at the transition state of Escherichia coli methylthioadenosine nucleosidase (EcMTAN) by transition state analysis and crystallography. We analyzed the EcMTAN mass in complex with a femtomolar transition state analogue to determine whether the inhibitor and nucleophilic water could be detected in the gas phase. EcMTAN-inhibitor and EcMTAN-inhibitor-nucleophilic water complexes were identified by high-resolution mass spectrometry under nondenaturing conditions. The enzyme-inhibitor-water complex is sufficiently stable to exist in the gas phase.
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Affiliation(s)
- Shanzhi Wang
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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18
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Schramm VL. Enzymatic transition states, transition-state analogs, dynamics, thermodynamics, and lifetimes. Annu Rev Biochem 2011; 80:703-32. [PMID: 21675920 DOI: 10.1146/annurev-biochem-061809-100742] [Citation(s) in RCA: 165] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Experimental analysis of enzymatic transition-state structures uses kinetic isotope effects (KIEs) to report on bonding and geometry differences between reactants and the transition state. Computational correlation of experimental values with chemical models permits three-dimensional geometric and electrostatic assignment of transition states formed at enzymatic catalytic sites. The combination of experimental and computational access to transition-state information permits (a) the design of transition-state analogs as powerful enzymatic inhibitors, (b) exploration of protein features linked to transition-state structure, (c) analysis of ensemble atomic motions involved in achieving the transition state, (d) transition-state lifetimes, and (e) separation of ground-state (Michaelis complexes) from transition-state effects. Transition-state analogs with picomolar dissociation constants have been achieved for several enzymatic targets. Transition states of closely related isozymes indicate that the protein's dynamic architecture is linked to transition-state structure. Fast dynamic motions in catalytic sites are linked to transition-state generation. Enzymatic transition states have lifetimes of femtoseconds, the lifetime of bond vibrations. Binding isotope effects (BIEs) reveal relative reactant and transition-state analog binding distortion for comparison with actual transition states.
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Affiliation(s)
- Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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19
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Wang R, Ibáñez G, Islam K, Zheng W, Blum G, Sengelaub C, Luo M. Formulating a fluorogenic assay to evaluate S-adenosyl-L-methionine analogues as protein methyltransferase cofactors. MOLECULAR BIOSYSTEMS 2011; 7:2970-81. [PMID: 21866297 DOI: 10.1039/c1mb05230f] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protein methyltransferases (PMTs) catalyze arginine and lysine methylation of diverse histone and nonhistone targets. These posttranslational modifications play essential roles in regulating multiple cellular events in an epigenetic manner. In the recent process of defining PMT targets, S-adenosyl-L-methionine (SAM) analogues have emerged as powerful small molecule probes to label and profile PMT targets. To examine efficiently the reactivity of PMTs and their variants on SAM analogues, we transformed a fluorogenic PMT assay into a ready high throughput screening (HTS) format. The reformulated fluorogenic assay is featured by its uncoupled but more robust character with the first step of accumulation of the commonly-shared reaction byproduct S-adenosyl-L-homocysteine (SAH), followed by SAH-hydrolase-mediated fluorogenic quantification. The HTS readiness and robustness of the assay were demonstrated by its excellent Z' values of 0.83-0.95 for the so-far-examined 8 human PMTs with SAM as a cofactor (PRMT1, PRMT3, CARM1, SUV39H2, SET7/9, SET8, G9a and GLP1). The fluorogenic assay was further implemented to screen the PMTs against five SAM analogues (allyl-SAM, propargyl-SAM, (E)-pent-2-en-4-ynyl-SAM (EnYn-SAM), (E)-hex-2-en-5-ynyl-SAM (Hey-SAM) and 4-propargyloxy-but-2-enyl-SAM (Pob-SAM)). Among the examined 8 × 5 pairs of PMTs and SAM analogues, native SUV39H2, G9a and GLP1 showed promiscuous activity on allyl-SAM. In contrast, the bulky SAM analogues, such as EnYn-SAM, Hey-SAM and Pob-SAM, are inert toward the panel of human PMTs. These findings therefore provide the useful structure-activity guidance to further evolve PMTs and SAM analogues for substrate labeling. The current assay format is ready to screen methyltransferase variants on structurally-diverse SAM analogues.
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Affiliation(s)
- Rui Wang
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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20
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Parveen N, Cornell KA. Methylthioadenosine/S-adenosylhomocysteine nucleosidase, a critical enzyme for bacterial metabolism. Mol Microbiol 2010; 79:7-20. [PMID: 21166890 DOI: 10.1111/j.1365-2958.2010.07455.x] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The importance of methylthioadenosine/S-adenosylhomocysteine (MTA/SAH) nucleosidase in bacteria has started to be appreciated only in the past decade. A comprehensive analysis of its various roles here demonstrates that it is an integral component of the activated methyl cycle, which recycles adenine and methionine through S-adenosylmethionine (SAM)-mediated methylation reactions, and also produces the universal quorum-sensing signal, autoinducer-2 (AI-2). SAM is also essential for synthesis of polyamines, N-acylhomoserine lactone (autoinducer-1), and production of vitamins and other biomolecules formed by SAM radical reactions. MTA, SAH and 5'-deoxyadenosine (5'dADO) are product inhibitors of these reactions, and are substrates of MTA/SAH nucleosidase, underscoring its importance in a wide array of metabolic reactions. Inhibition of this enzyme by certain substrate analogues also limits synthesis of autoinducers and hence causes reduction in biofilm formation and may attenuate virulence. Interestingly, the inhibitors of MTA/SAH nucleosidase are very effective against the Lyme disease causing spirochaete, Borrelia burgdorferi, which uniquely expresses three homologous functional enzymes. These results indicate that inhibition of this enzyme can affect growth of different bacteria by affecting different mechanisms. Therefore, new inhibitors are currently being explored for development of potential novel broad-spectrum antimicrobials.
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Affiliation(s)
- Nikhat Parveen
- Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 225 Warren Street, Newark, NJ 07103-3535, USA.
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21
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Zhang Y, Deng H, Schramm VL. Leaving group activation and pyrophosphate ionic state at the catalytic site of Plasmodium falciparum orotate phosphoribosyltransferase. J Am Chem Soc 2010; 132:17023-31. [PMID: 21067187 DOI: 10.1021/ja107806j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Plasmodium falciparum orotate phosphoribosyltransferase (PfOPRT) catalyzes the reversible pyrophosphorolysis of orotidine 5'-monophosphate (OMP). Transition-state analysis from kinetic isotope effects supports a dianionic orotic acid (OA) leaving group. Isotope-edited Fourier transform infrared (FTIR) spectrometry complemented by homology modeling and quantum chemical calculations were used to characterize the orotate hydrogen-bond network for PfOPRT. Bond stretch frequencies for C(2)═O and C(4)═O of OMP were established from (13)C-edited FTIR difference spectra. Both frequencies were shifted downward by 20 cm(-1) upon formation of the Michaelis complex. Hydrogen-bond interactions to the orotate moiety induce strong leaving group polarization by ground-state destabilization. The C(2)═O bond is 2.7 Å from two conserved water molecules, and the C(4)═O bond is within 2.4 Å of the NH(2)(ω) of Arg241 and the peptide NH of Phe97. Relative to free OMP, the N1 atom of PfOPRT-bound OMP indicates a ΔpK(a) of -4.6. The decreased basicity of N1 supports leaving group activation through a hydrogen-bond network at the PfOPRT active site. PfOPRT in complex with (18)O-PPi and a proposed transition-state analogue revealed a trianionic PPi nucleophile with no significant P··O bond polarization, supporting a mechanism proceeding through the migration of the ribocation toward the PPi. These results along with previous PfOPRT transition-state analyses provide reaction coordinate information for the PfOPRT-catalyzed OMP pyrophosphorolysis reaction.
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Affiliation(s)
- Yong Zhang
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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22
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Longshaw AI, Adanitsch F, Gutierrez JA, Evans GB, Tyler PC, Schramm VL. Design and synthesis of potent "sulfur-free" transition state analogue inhibitors of 5'-methylthioadenosine nucleosidase and 5'-methylthioadenosine phosphorylase. J Med Chem 2010; 53:6730-46. [PMID: 20718423 DOI: 10.1021/jm100898v] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) is a dual substrate bacterial enzyme involved in S-adenosylmethionine (SAM) related quorum sensing pathways that regulates virulence in many bacterial species. MTANs from many bacteria are directly involved in the quorum sensing mechanism by regulating the synthesis of autoinducer molecules that are used by bacterial communities to communicate. In humans, 5'-methylthioadenosine phosphorylase (MTAP) is involved in polyamine biosynthesis as well as in purine and SAM salvage pathways and thus has been identified as an anticancer target. Previously we have described the synthesis and biological activity of several aza-C-nucleoside mimics with a sulfur atom at the 5' position that are potent E. coli MTAN and human MTAP inhibitors. Because of the possibility that the sulfur may affect bioavailability, we were interested in synthesizing "sulfur-free" analogues. Herein we describe the preparation of a series of "sulfur-free" transition state analogue inhibitors of E. coli MTAN and human MTAP that have low nano- to picomolar dissociation constants and are potentially novel bacterial anti-infective and anticancer drug candidates.
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Affiliation(s)
- Alistair I Longshaw
- Carbohydrate Chemistry Team, Industrial Research Limited, P.O. Box 31310, Lower Hutt, New Zealand
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23
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Zhang Y, Schramm VL. Pyrophosphate interactions at the transition states of Plasmodium falciparum and human orotate phosphoribosyltransferases. J Am Chem Soc 2010; 132:8787-94. [PMID: 20527751 DOI: 10.1021/ja102849w] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Orotate phosphoribosyltransferases from Plasmodium falciparum and human sources (PfOPRT and HsOPRT) use orotidine as a slow substrate in the pyrophosphorolysis reaction. With orotidine, intrinsic kinetic isotope effects (KIEs) can be measured for pyrophosphorolysis, providing the first use of pyrophosphate (PPi) in solving an enzymatic transition state. Transition-state structures of PfOPRT and HsOPRT were solved through quantum chemical matching of computed and experimental intrinsic KIEs and can be compared to transition states solved with pyrophosphate analogues as slow substrates. PfOPRT and HsOPRT are characterized by late transition states with fully dissociated orotate, well-developed ribocations, and weakly bonded PPi nucleophiles. The leaving orotates are 2.8 A distant from the anomeric carbons at the transition states. Weak participation of the PPi nucleophiles gives C1'-O(PPi) bond distances of approximately 2.3 A. These transition states are characterized by C2'-endo ribosyl pucker, based on the beta-secondary [2'-(3)H] KIEs. The geometry at the 5'-region is similar for both enzymes, with C3'-C4'-C5'-O5' dihedral angles near -170 degrees . These novel phosphoribosyltransferase transition states are similar to but occur earlier in the reaction coordinate than those previously determined with orotidine 5'-monophosphate and phosphonoacetic acid as substrates. The similarity between the transition states with different substrate analogues supports similar transition state structures imposed by PfOPRT and HsOPRT even with distinct reactants. We propose that the transition state similarity with different nucleophiles is determined, in part, by the geometric constraints imposed by the catalytic sites.
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Affiliation(s)
- Yong Zhang
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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24
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Zhang Y, Luo M, Schramm VL. Transition states of Plasmodium falciparum and human orotate phosphoribosyltransferases. J Am Chem Soc 2009; 131:4685-94. [PMID: 19292447 PMCID: PMC2669657 DOI: 10.1021/ja808346y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Orotate phosphoribosyltransferases (OPRT) catalyze the formation of orotidine 5'-monophosphate (OMP) from alpha-D-phosphoribosylpyrophosphate (PRPP) and orotate, an essential step in the de novo biosynthesis of pyrimidines. Pyrimidine de novo biosynthesis is required in Plasmodium falciparum , and thus OPRT of the parasite (PfOPRT) is a target for antimalarial drugs. De novo biosynthesis of pyrimidines is also a feature of rapidly proliferating cancer cells. Human OPRT (HsOPRT) is therefore a target for neoplastic and autoimmune diseases. One approach to the inhibition of OPRTs is through analogues that mimic the transition states of PfOPRT and HsOPRT. The transition state structures of these OPRTs were analyzed by kinetic isotope effects (KIEs), substrate specificity, and computational chemistry. With phosphonoacetic acid (PA), an analogue of pyrophosphate, the intrinsic KIEs of [1'-(14)C], [1, 3-(15)N(2)], [3-(15)N], [1'-(3)H], [2'-(3)H], [4'-(3)H], and [5'-(3)H(2)] are 1.034, 1.028, 0.997, 1.261, 1.116, 0.974, and 1.013 for PfOPRT and 1.035, 1.025, 0.993, 1.199, 1.129, 0.962, and 1.019 for HsOPRT, respectively. Transition state structures of PfOPRT and HsOPRT were determined computationally by matching the calculated and intrinsic KIEs. The enzymes form late associative D(N)*A(N)(double dagger) transition states with complete orotate loss and partially associative nucleophile. The C1'-O(PA) distances are approximately 2.1 A at these transition states. The modest [1'-(14)C] KIEs and large [1'-(3)H] KIEs are characteristic of D(N)*A(N)(double dagger) transition states. The large [2'-(3)H] KIEs indicate a ribosyl 2'-C-endo conformation at the transition states. p-Nitrophenyl beta-D-ribose 5'-phosphate is a poor substrate of PfOPRT and HsOPRT but is a nanomolar inhibitor, supporting a reaction coordinate with strong leaving group activation.
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Affiliation(s)
- Yong Zhang
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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25
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Transition state analogs of 5'-methylthioadenosine nucleosidase disrupt quorum sensing. Nat Chem Biol 2009; 5:251-7. [PMID: 19270684 PMCID: PMC2743263 DOI: 10.1038/nchembio.153] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Accepted: 02/04/2009] [Indexed: 02/07/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) is a bacterial enzyme involved in S-adenosylmethionine-related quorum sensing pathways that induce bacterial pathogenesis factors. Transition state analogs MT-DADMe-Immucillin-A, EtT-DADMe-Immucillin-A and BuT-DADMe-Immucillin-A are slow-onset, tight-binding inhibitors of Vibrio cholerae MTAN (VcMTAN), with equilibrium dissociation constants of 73, 70 and 208 pM, respectively. Structural analysis of VcMTAN with BuT-DADMe-Immucillin-A revealed interactions contributing to the high affinity. We found that in V. cholerae cells, these compounds are potent MTAN inhibitors with IC(50) values of 27, 31 and 6 nM for MT-, EtT- and BuT-DADMe-Immucillin-A, respectively; the compounds disrupt autoinducer production in a dose-dependent manner without affecting growth. MT- and BuT-DADMe-Immucillin-A also inhibited autoinducer-2 production in enterohemorrhagic Escherichia coli O157:H7 with IC(50) values of 600 and 125 nM, respectively. BuT-DADMe-Immucillin-A inhibition of autoinducer-2 production in both strains persisted for several generations and caused reduction in biofilm formation. These results support MTAN's role in quorum sensing and its potential as a target for bacterial anti-infective drug design.
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Abstract
Methionine adenosyltransferases (MATs) are the family of enzymes that synthesize the main biological methyl donor, S-adenosylmethionine. The high sequence conservation among catalytic subunits from bacteria and eukarya preserves key residues that control activity and oligomerization, which is reflected in the protein structure. However, structural differences among complexes with substrates and products have led to proposals of several reaction mechanisms. In parallel, folding studies begin to explain how the three intertwined domains of the catalytic subunit are produced, and to highlight the importance of certain intermediates in attaining the active final conformation. This review analyzes the available structural data and proposes a consensus interpretation that facilitates an understanding of the pathological problems derived from impairment of MAT function. In addition, new research opportunities directed toward clarification of aspects that remain obscure are also identified.
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Affiliation(s)
- G D Markham
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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27
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Transition state analogs of 5'-methylthioadenosine nucleosidase disrupt quorum sensing. Nat Chem Biol 2009. [PMID: 19270684 DOI: 10.1038/nchembio.153.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) is a bacterial enzyme involved in S-adenosylmethionine-related quorum sensing pathways that induce bacterial pathogenesis factors. Transition state analogs MT-DADMe-Immucillin-A, EtT-DADMe-Immucillin-A and BuT-DADMe-Immucillin-A are slow-onset, tight-binding inhibitors of Vibrio cholerae MTAN (VcMTAN), with equilibrium dissociation constants of 73, 70 and 208 pM, respectively. Structural analysis of VcMTAN with BuT-DADMe-Immucillin-A revealed interactions contributing to the high affinity. We found that in V. cholerae cells, these compounds are potent MTAN inhibitors with IC(50) values of 27, 31 and 6 nM for MT-, EtT- and BuT-DADMe-Immucillin-A, respectively; the compounds disrupt autoinducer production in a dose-dependent manner without affecting growth. MT- and BuT-DADMe-Immucillin-A also inhibited autoinducer-2 production in enterohemorrhagic Escherichia coli O157:H7 with IC(50) values of 600 and 125 nM, respectively. BuT-DADMe-Immucillin-A inhibition of autoinducer-2 production in both strains persisted for several generations and caused reduction in biofilm formation. These results support MTAN's role in quorum sensing and its potential as a target for bacterial anti-infective drug design.
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28
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Luo M, Schramm VL. Ribosyl geometry in the transition state of Streptococcus pneumoniae methylthioadenosine nucleosidase from the 3'-(2)H kinetic isotope effect. J Am Chem Soc 2008; 130:11617-9. [PMID: 18693725 PMCID: PMC9768846 DOI: 10.1021/ja804578m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Synthesis of [3'-2H]-labeled 5'-methylthioadenosine (MTA) derivatives permitted measurement of the [3'-2H] KIE of the reaction catalyzed by Streptococcus pneumoniae methylthioadenosine nucleosidase (spMTAN). The key [3'-2H] KIE revealed the partial 3'-OH polarization and H3'-endo-->exo ribosyl configuration at the spMTAN transition state. A new understanding of the transition state stabilization of spMTAN-catalyzed hydrolysis is uncovered in structural features at the spMTAN transition state.
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