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Lopez-Schenk R, Collins NL, Schenk NA, Beard DA. Integrated Functions of Cardiac Energetics, Mechanics, and Purine Nucleotide Metabolism. Compr Physiol 2023; 14:5345-5369. [PMID: 38158366 PMCID: PMC10956446 DOI: 10.1002/cphy.c230011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Purine nucleotides play central roles in energy metabolism in the heart. Most fundamentally, the free energy of hydrolysis of the adenine nucleotide adenosine triphosphate (ATP) provides the thermodynamic driving force for numerous cellular processes including the actin-myosin crossbridge cycle. Perturbations to ATP supply and/or demand in the myocardium lead to changes in the homeostatic balance between purine nucleotide synthesis, degradation, and salvage, potentially affecting myocardial energetics and, consequently, myocardial mechanics. Indeed, both acute myocardial ischemia and decompensatory remodeling of the myocardium in heart failure are associated with depletion of myocardial adenine nucleotides and with impaired myocardial mechanical function. Yet there remain gaps in the understanding of mechanistic links between adenine nucleotide degradation and contractile dysfunction in heart disease. The scope of this article is to: (i) review current knowledge of the pathways of purine nucleotide depletion and salvage in acute ischemia and in chronic heart disease; (ii) review hypothesized mechanisms linking myocardial mechanics and energetics with myocardial adenine nucleotide regulation; and (iii) highlight potential targets for treating myocardial metabolic and mechanical dysfunction associated with these pathways. It is hypothesized that an imbalance in the degradation, salvage, and synthesis of adenine nucleotides leads to a net loss of adenine nucleotides in both acute ischemia and under chronic high-demand conditions associated with the development of heart failure. This reduction in adenine nucleotide levels results in reduced myocardial ATP and increased myocardial inorganic phosphate. Both of these changes have the potential to directly impact tension development and mechanical work at the cellular level. © 2024 American Physiological Society. Compr Physiol 14:5345-5369, 2024.
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Affiliation(s)
- Rachel Lopez-Schenk
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Nicole L Collins
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Noah A Schenk
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Daniel A Beard
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
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2
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Zhou Y, Xu X, Wei Y, Cheng Y, Guo Y, Khudyakov I, Liu F, He P, Song Z, Li Z, Gao Y, Ang EL, Zhao H, Zhang Y, Zhao S. A widespread pathway for substitution of adenine by diaminopurine in phage genomes. Science 2021; 372:512-516. [PMID: 33926954 DOI: 10.1126/science.abe4882] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 03/05/2021] [Indexed: 01/04/2023]
Abstract
DNA modifications vary in form and function but generally do not alter Watson-Crick base pairing. Diaminopurine (Z) is an exception because it completely replaces adenine and forms three hydrogen bonds with thymine in cyanophage S-2L genomic DNA. However, the biosynthesis, prevalence, and importance of Z genomes remain unexplored. Here, we report a multienzyme system that supports Z-genome synthesis. We identified dozens of globally widespread phages harboring such enzymes, and we further verified the Z genome in one of these phages, Acinetobacter phage SH-Ab 15497, by using liquid chromatography with ultraviolet and mass spectrometry. The Z genome endows phages with evolutionary advantages for evading the attack of host restriction enzymes, and the characterization of its biosynthetic pathway enables Z-DNA production on a large scale for a diverse range of applications.
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Affiliation(s)
- Yan Zhou
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.,Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Xuexia Xu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai 200061, China
| | - Yifeng Wei
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Yu Cheng
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yu Guo
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ivan Khudyakov
- All-Russian Research Institute for Agricultural Microbiology, St. Petersburg 196608, Russia
| | - Fuli Liu
- Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ping He
- Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zhangyue Song
- Biomedical Big Data Platform, SIAIS, ShanghaiTech University, Shanghai 201210, China
| | - Zhi Li
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Yan Gao
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Ee Lui Ang
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Huimin Zhao
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A*STAR), Singapore. .,Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yan Zhang
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China. .,Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China
| | - Suwen Zhao
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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3
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Wauters L, Terheyden S, Gilsbach BK, Leemans M, Athanasopoulos PS, Guaitoli G, Wittinghofer A, Gloeckner CJ, Versées W, Kortholt A. Biochemical and kinetic properties of the complex Roco G-protein cycle. Biol Chem 2019; 399:1447-1456. [PMID: 30067506 DOI: 10.1515/hsz-2018-0227] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022]
Abstract
Roco proteins have come into focus after mutations in the gene coding for the human Roco protein Leucine-rich repeat kinase 2 (LRRK2) were discovered to be one of the most common genetic causes of late onset Parkinson's disease. Roco proteins are characterized by a Roc domain responsible for GTP binding and hydrolysis, followed by a COR dimerization device. The regulation and function of this RocCOR domain tandem is still not completely understood. To fully biochemically characterize Roco proteins, we performed a systematic survey of the kinetic properties of several Roco protein family members, including LRRK2. Together, our results show that Roco proteins have a unique G-protein cycle. Our results confirm that Roco proteins have a low nucleotide affinity in the micromolar range and thus do not strictly depend on G-nucleotide exchange factors. Measurement of multiple and single turnover reactions shows that neither Pi nor GDP release are rate-limiting, while this is the case for the GAP-mediated GTPase reaction of some small G-proteins like Ras and for most other high affinity Ras-like proteins, respectively. The KM values of the reactions are in the range of the physiological GTP concentration, suggesting that LRRK2 functioning might be regulated by the cellular GTP level.
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Affiliation(s)
- Lina Wauters
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.,Department of Cell Biochemistry, University of Groningen, Groningen NL-9747 AG, The Netherlands.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Susanne Terheyden
- Department of Cell Biochemistry, University of Groningen, Groningen NL-9747 AG, The Netherlands.,Structural Biology Group, Max-Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Bernd K Gilsbach
- German Center for Neurodegenerative Diseases (DZNE), Otfried-Müller-Str. 23, D-72076 Tübingen, Germany
| | - Margaux Leemans
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | | | - Giambattista Guaitoli
- German Center for Neurodegenerative Diseases (DZNE), Otfried-Müller-Str. 23, D-72076 Tübingen, Germany
| | - Alfred Wittinghofer
- Structural Biology Group, Max-Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Christian Johannes Gloeckner
- German Center for Neurodegenerative Diseases (DZNE), Otfried-Müller-Str. 23, D-72076 Tübingen, Germany.,University of Tübingen, Institute for Ophthalmic Research, Center for Ophthalmology, D-72076 Tübingen, Germany
| | - Wim Versées
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Groningen NL-9747 AG, The Netherlands
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4
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Karnawat V, Mehrotra S, Balaram H, Puranik M. Exquisite Modulation of the Active Site of Methanocaldococcus jannaschii Adenylosuccinate Synthetase in Forward Reaction Complexes. Biochemistry 2016; 55:2491-9. [PMID: 27050719 DOI: 10.1021/acs.biochem.5b01386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In enzymes that conduct complex reactions involving several substrates and chemical transformations, the active site must reorganize at each step to complement the transition state of that chemical step. Adenylosuccinate synthetase (ADSS) utilizes a molecule each of guanosine 5'-monophosphate (GTP) and aspartate to convert inosine 5'-monophosphate (IMP) into succinyl adenosine 5'-monophosphate (sAMP) through several kinetic intermediates. Here we followed catalysis by ADSS through high-resolution vibrational spectral fingerprints of each substrate and intermediate involved in the forward reaction. Vibrational spectra show differential ligand distortion at each step of catalysis, and band positions of substrates are influenced by binding of cosubstrates. We found that the bound IMP is distorted toward its N1-deprotonated form even in the absence of any other ligands. Several specific interactions between GTP and active-site amino acid residues result in large Raman shifts and contribute substantially to intrinsic binding energy. When both IMP and GTP are simultaneously bound to ADSS, IMP is converted into an intermediate 6-phosphoryl inosine 5'-monophosphate (6-pIMP). The 6-pIMP·ADSS complex was found to be stable upon binding of the third ligand, hadacidin (HDA), an analogue of l-aspartate. We find that in the absence of HDA, 6-pIMP is quickly released from ADSS, is unstable in solution, and converts back into IMP. HDA allosterically stabilizes ADSS through local conformational rearrangements. We captured this complex and determined the spectra and structure of 6-pIMP in its enzyme-bound state. These results provide important insights into the exquisite tuning of active-site interactions with changing substrate at each kinetic step of catalysis.
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Affiliation(s)
- Vishakha Karnawat
- Indian Institute of Science Education and Research , Pune 411008, India
| | - Sonali Mehrotra
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India
| | - Hemalatha Balaram
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India
| | - Mrinalini Puranik
- Indian Institute of Science Education and Research , Pune 411008, India
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5
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Karnawat V, Puranik M. Solution structure of ligands involved in purine salvage pathway. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 151:679-686. [PMID: 26163792 DOI: 10.1016/j.saa.2015.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/30/2015] [Accepted: 07/01/2015] [Indexed: 06/04/2023]
Abstract
Analogues of intermediates involved in the purine salvage pathway can be exploited as potential drug molecules against enzymes of protozoan parasites. To develop such analogues we need knowledge of the solution structures, predominant tautomer at physiological pH and protonation-state of the corresponding natural ligand. In this regard, we have employed ultraviolet resonance Raman spectroscopy (UVRR) in combination with density functional theory (DFT) to study the solution structures of two relatively unexplored intermediates, 6-phosphoryl IMP (6-pIMP) and succinyl adenosine-5'-monophosphate (sAMP), of purine salvage pathway. These molecules are intermediates in a two step enzymatic process that converts inosine-5'-monpophosphate (IMP) to adenosine-5'-monophosphate (AMP). Experimental data on the molecular structure of these ligands is lacking. We report UVRR spectra of these two ligands, obtained at an excitation wavelength of 260 nm. Using isotope induced shifts and DFT calculations we assigned observed spectra to computed normal modes. We find that sAMP exists as neutral species at physiological pH and the predominant tautomer in solution bears proton at N10 position of purine ring. Though transient in solution, 6-pIMP is captured in the enzyme-bound form. This work provides the structural information of these ligands in solution state at physiological pH. We further compare these structures with the structures of AMP and IMP. Despite the presence of similar purine rings in AMP and sAMP, their UVRR spectra are found to be very different. Similarly, though the purine ring in 6-pIMP resembles that of IMP, UVRR spectra of the two molecules are distinct. These differences in the vibrational spectra provide direct information on the effects of exocyclic groups on the skeletal structures of these molecules. Our results identify key bands in the vibrational spectra of these ligands which may serve as markers of hydrogen bonding interactions upon binding to the active-sites of enzymes.
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Affiliation(s)
- Vishakha Karnawat
- Indian Institute of Science Education and Research, Pune 411008, India
| | - Mrinalini Puranik
- Indian Institute of Science Education and Research, Pune 411008, India.
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Blundell RD, Williams SJ, Morrow CA, Ericsson DJ, Kobe B, Fraser JA. Purification, crystallization and preliminary X-ray analysis of adenylosuccinate synthetase from the fungal pathogen Cryptococcus neoformans. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1033-6. [PMID: 23989157 PMCID: PMC3758157 DOI: 10.1107/s1744309113021921] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/06/2013] [Indexed: 03/16/2023]
Abstract
With increasingly large immunocompromised populations around the world, opportunistic fungal pathogens such as Cryptococcus neoformans are a growing cause of morbidity and mortality. To combat the paucity of antifungal compounds, new drug targets must be investigated. Adenylosuccinate synthetase is a crucial enzyme in the ATP de novo biosynthetic pathway, catalyzing the formation of adenylosuccinate from inosine monophosphate and aspartate. Although the enzyme is ubiquitous and well characterized in other kingdoms, no crystallographic studies on the fungal protein have been performed. Presented here are the expression, purification, crystallization and initial crystallographic analyses of cryptococcal adenylosuccinate synthetase. The crystals had the symmetry of space group P2(1)2(1)2(1) and diffracted to 2.2 Å resolution.
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Affiliation(s)
- Ross D. Blundell
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Simon J. Williams
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Carl A. Morrow
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Daniel J. Ericsson
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Bostjan Kobe
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - James A. Fraser
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
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7
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Information properties of naturally-occurring proteins: Fourier analysis and complexity phase plots. Protein J 2012; 31:550-63. [PMID: 22814572 DOI: 10.1007/s10930-012-9432-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In previous work from this lab, the information in natural proteins was investigated with Ribonuclease A (RNase A) serving as the source. The signature traits were investigated at three structure levels: primary through tertiary. The present paper travels further by charting the primary structure information of about half a million molecules. This was feasible given abundant sequence archives for both living and viral systems. Notably, a method is presented for evaluating primary structure information, based on Fourier analysis and spectral complexity. Significantly, the results show certain complexity traits to be universal for living sources. Viruses, by contrast, encode protein collections which are case-specific and complexity-divergent. The results have ramifications for discriminating collections on the basis of sequence information. This discrimination offers new strategies for selecting drug targets.
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8
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Iancu CV, Zhou Y, Borza T, Fromm HJ, Honzatko RB. Cavitation as a mechanism of substrate discrimination by adenylosuccinate synthetases. Biochemistry 2006; 45:11703-11. [PMID: 16981730 PMCID: PMC4869520 DOI: 10.1021/bi0607498] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Adenylosuccinate synthetase catalyzes the first committed step in the de novo biosynthesis of AMP, coupling L-aspartate and IMP to form adenylosuccinate. Km values of IMP and 2'-deoxy-IMP are nearly identical with each substrate supporting comparable maximal velocities. Nonetheless, the Km value for L-aspartate and the Ki value for hadacidin (a competitive inhibitor with respect to L-aspartate) are 29-57-fold lower in the presence of IMP than in the presence of 2'-deoxy-IMP. Crystal structures of the synthetase ligated with hadacidin, GDP, and either 6-phosphoryl-IMP or 2'-deoxy-6-phosphoryl-IMP are identical except for the presence of a cavity normally occupied by the 2'-hydroxyl group of IMP. In the presence of 6-phosphoryl-IMP and GDP (hadacidin absent), the L-aspartate pocket can retain its fully ligated conformation, forming hydrogen bonds between the 2'-hydroxyl group of IMP and sequence-invariant residues. In the presence of 2'-deoxy-6-phosphoryl-IMP and GDP, however, the L-aspartate pocket is poorly ordered. The absence of the 2'-hydroxyl group of the deoxyribonucleotide may destabilize binding of the ligand to the L-aspartate pocket by disrupting hydrogen bonds that maintain a favorable protein conformation and by the introduction of a cavity into the fully ligated active site. At an approximate energy cost of 2.2 kcal/mol, the unfavorable thermodynamics of cavity formation may be the major factor in destabilizing ligands at the L-aspartate pocket.
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9
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Endrizzi JA, Kim H, Anderson PM, Baldwin EP. Mechanisms of product feedback regulation and drug resistance in cytidine triphosphate synthetases from the structure of a CTP-inhibited complex. Biochemistry 2006; 44:13491-9. [PMID: 16216072 PMCID: PMC2891682 DOI: 10.1021/bi051282o] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytidine triphosphate synthetases (CTPSs) synthesize CTP and regulate its intracellular concentration through direct interactions with the four ribonucleotide triphosphates. In particular, CTP product is a feedback inhibitor that competes with UTP substrate. Selected CTPS mutations that impart resistance to pyrimidine antimetabolite inhibitors also relieve CTP inhibition and cause a dramatic increase in intracellular CTP concentration, indicating that the drugs act by binding to the CTP inhibitory site. Resistance mutations map to a pocket that, although adjacent, does not coincide with the expected UTP binding site in apo Escherichia coli CTPS [EcCTPS; Endrizzi, J. A., et al. (2004) Biochemistry 43, 6447-6463], suggesting allosteric rather than competitive inhibition. Here, bound CTP and ADP were visualized in catalytically active EcCTPS crystals soaked in either ATP and UTP substrates or ADP and CTP products. The CTP cytosine ring resides in the pocket predicted by the resistance mutations, while the triphosphate moiety overlaps the putative UTP triphosphate binding site, explaining how CTP competes with UTP while CTP resistance mutations are acquired without loss of catalytic efficiency. Extensive complementarity and interaction networks at the interfacial binding sites provide the high specificity for pyrimidine triphosphates and mediate nucleotide-dependent tetramer formation. Overall, these results depict a novel product inhibition strategy in which shared substrate and product moieties bind to a single subsite while specificity is conferred by separate subsites. This arrangement allows for independent adaptation of UTP and CTP binding affinities while efficiently utilizing the enzyme surface.
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Affiliation(s)
| | | | | | - Enoch P. Baldwin
- To whom correspondence should be addressed. . Phone: (530) 752-1108. Fax: (530) 752-3085
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10
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Mao L, Wang Y, Liu Y, Hu X. Molecular determinants for ATP-binding in proteins: a data mining and quantum chemical analysis. J Mol Biol 2004; 336:787-807. [PMID: 15095988 DOI: 10.1016/j.jmb.2003.12.056] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2003] [Revised: 11/29/2003] [Accepted: 12/11/2003] [Indexed: 11/26/2022]
Abstract
Adenosine 5'-triphosphate (ATP) plays an essential role in all forms of life. Molecular recognition of ATP in proteins is a subject of great importance for understanding enzymatic mechanism and for drug design. We have carried out a large-scale data mining of the Protein Data Bank (PDB) to analyze molecular determinants for recognition of the adenine moiety of ATP by proteins. Non-bonded intermolecular interactions (hydrogen bonding, pi-pi stacking interactions, and cation-pi interactions) between adenine base and surrounding residues in its binding pockets are systematically analyzed for 68 non-redundant, high-resolution crystal structures of adenylate-binding proteins. In addition to confirming the importance of the widely known hydrogen bonding, we found out that cation-pi interactions between adenine base and positively charged residues (Lys and Arg) and pi-pi stacking interactions between adenine base and surrounding aromatic residues (Phe, Tyr, Trp) are also crucial for adenine binding in proteins. On average, there exist 2.7 hydrogen bonding interactions, 1.0 pi-pi stacking interactions, and 0.8 cation-pi interactions in each adenylate-binding protein complex. Furthermore, a high-level quantum chemical analysis was performed to analyze contributions of each of the three forms of intermolecular interactions (i.e. hydrogen bonding, pi-pi stacking interactions, and cation-pi interactions) to the overall binding force of the adenine moiety of ATP in proteins. Intermolecular interaction energies for representative configurations of intermolecular complexes were analyzed using the supermolecular approach at the MP2/6-311 + G* level, which resulted in substantial interaction strengths for all the three forms of intermolecular interactions. This work represents a timely undertaking at a historical moment when a large number of X-ray crystallographic structures of proteins with bound ATP ligands have become available, and when high-level quantum chemical analysis of intermolecular interactions of large biomolecular systems becomes computationally feasible. The establishment of the molecular basis for recognition of the adenine moiety of ATP in proteins will directly impact molecular design of ATP-binding site targeted enzyme inhibitors such as kinase inhibitors.
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Affiliation(s)
- Lisong Mao
- Department of Chemistry, University of Toledo, Toledo, OH 43606-3390, USA
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11
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Borza T, Iancu CV, Pike E, Honzatko RB, Fromm HJ. Variations in the response of mouse isozymes of adenylosuccinate synthetase to inhibitors of physiological relevance. J Biol Chem 2003; 278:6673-9. [PMID: 12482871 DOI: 10.1074/jbc.m210838200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vertebrates have acidic and basic isozymes of adenylosuccinate synthetase, which participate in the first committed step of de novo AMP biosynthesis and/or the purine nucleotide cycle. These isozymes differ in their kinetic properties and N-leader sequences, and their regulation may vary with tissue type. Recombinant acidic and basic synthetases from mouse, in the presence of active site ligands, behave in analytical ultracentrifugation as dimers. Active site ligands enhance thermal stability of both isozymes. Truncated forms of both isozymes retain the kinetic parameters and the oligomerization status of the full-length proteins. AMP potently inhibits the acidic isozyme competitively with respect to IMP. In contrast, AMP weakly inhibits the basic isozyme noncompetitively with respect to all substrates. IMP inhibition of the acidic isozyme is competitive, and that of the basic isozyme noncompetitive, with respect to GTP. Fructose 1,6-bisphosphate potently inhibits both isozymes competitively with respect to IMP but becomes noncompetitive at saturating substrate concentrations. The above, coupled with structural information, suggests antagonistic interactions between the active sites of the basic isozyme, whereas active sites of the acidic isozyme seem functionally independent. Fructose 1,6-bisphosphate and IMP together may be dynamic regulators of the basic isozyme in muscle, causing potent inhibition of the synthetase under conditions of high AMP deaminase activity.
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Affiliation(s)
- Tudor Borza
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 5011, USA
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