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Jian Y, Maximowitsch E, Liu D, Adhikari S, Li L, Domratcheva T. Indications of 5' to 3' Interbase Electron Transfer as the First Step of Pyrimidine Dimer Formation Probed by a Dinucleotide Analog. Chemistry 2017; 23:7526-7537. [PMID: 28370554 DOI: 10.1002/chem.201700045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Indexed: 12/12/2022]
Abstract
Pyrimidine dimers are the most common DNA lesions generated under UV radiation. To reveal the molecular mechanisms behind their formation, it is of significance to reveal the roles of each pyrimidine residue. We thus replaced the 5'-pyrimidine residue with a photochemically inert xylene moiety (X). The electron-rich X can be readily oxidized but not reduced, defining the direction of interbase electron transfer (ET). Irradiation of the XpT dinucleotide under 254 nm UV light generates two major photoproducts: a pyrimidine (6-4) pyrimidone analog (6-4PP) and an analog of the so-called spore photoproduct (SP). Both products are formed by reaction at C4=O of the photo-excited 3'-thymidine (T), which indicates that excitation of a single "driver" residue is sufficient to trigger pyrimidine dimerization. Our quantum-chemical calculations demonstrated that photo-excited 3'-T accepts an electron from 5'-X. The resulting charge-separated radical pair lowers its energy upon formation of interbase covalent bonds, eventually yielding 6-4PP and SP.
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Affiliation(s)
- Yajun Jian
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, Indianapolis, Indiana, 46202, USA.,School of Chemistry & Chemical Engineering, Shaanxi Normal University (SNNU), No. 620, West Chang'an Avenue, Xi'an, Shaanxi, 710119, P. R. China
| | - Egle Maximowitsch
- Department of Biomolecular Mechanisms, Max-Planck Institute for Medical Research, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Degang Liu
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, Indianapolis, Indiana, 46202, USA
| | - Surya Adhikari
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, Indianapolis, Indiana, 46202, USA
| | - Lei Li
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, Indianapolis, Indiana, 46202, USA.,Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, 46202, USA
| | - Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max-Planck Institute for Medical Research, Jahnstrasse 29, 69120, Heidelberg, Germany
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Hayes EC, Jian Y, Li L, Stoll S. EPR Study of UV-Irradiated Thymidine Microcrystals Supports Radical Intermediates in Spore Photoproduct Formation. J Phys Chem B 2016; 120:10923-10931. [DOI: 10.1021/acs.jpcb.6b06587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Ellen C. Hayes
- Department
of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195, United States
| | - Yajun Jian
- Department
of Chemistry and Chemical Biology, 402 N. Blackford Street, LD 326, Indiana University—Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Lei Li
- Department
of Chemistry and Chemical Biology, 402 N. Blackford Street, LD 326, Indiana University—Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Stefan Stoll
- Department
of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195, United States
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Setlow P, Li L. Photochemistry and Photobiology of the Spore Photoproduct: A 50-Year Journey. Photochem Photobiol 2015; 91:1263-90. [PMID: 26265564 PMCID: PMC4631623 DOI: 10.1111/php.12506] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 07/21/2015] [Indexed: 02/06/2023]
Abstract
Fifty years ago, a new thymine dimer was discovered as the dominant DNA photolesion in UV-irradiated bacterial spores [Donnellan, J. E. & Setlow R. B. (1965) Science, 149, 308-310], which was later named the spore photoproduct (SP). Formation of SP is due to the unique environment in the spore core that features low hydration levels favoring an A-DNA conformation, high levels of calcium dipicolinate that acts as a photosensitizer, and DNA saturation with small, acid-soluble proteins that alters DNA structure and reduces side reactions. In vitro studies reveal that any of these factors alone can promote SP formation; however, SP formation is usually accompanied by the production of other DNA photolesions. Therefore, the nearly exclusive SP formation in spores is due to the combined effects of these three factors. Spore photoproduct photoreaction is proved to occur via a unique H-atom transfer mechanism between the two involved thymine residues. Successful incorporation of SP into an oligonucleotide has been achieved via organic synthesis, which enables structural studies that reveal minor conformational changes in the SP-containing DNA. Here, we review the progress on SP photochemistry and photobiology in the past 50 years, which indicates a very rich SP photobiology that may exist beyond endospores.
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Affiliation(s)
- Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Lei Li
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, Indiana, 46202
- Department of Biochemistry and Molecular Biology & Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana 46202
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Jian Y, Ames DM, Ouyang H, Li L. Photochemical reactions of microcrystalline thymidine. Org Lett 2015; 17:824-7. [PMID: 25668312 DOI: 10.1021/ol5036276] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nucleoside/nucleotide/oligonucleotide photoreactions usually result in a number of products simultaneously due to a wide range of conformers existing at a given time. Such a complicated reaction pattern makes it difficult for one to focus on a single DNA photoproduct and elucidate the requirements for its formation. A rare example of thymidine photoreaction in microcrystals is reported, where 5-thyminyl-5,6-dihydrothymine, e.g., the spore photoproduct (SP), is produced as the dominant species in ∼85% yield. This unprecedented high yield clears the major obstacle for future SP photochemistry studies in detail.
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Affiliation(s)
- Yajun Jian
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI) , 402 North Blackford Street, Indianapolis, Indiana 46202, United States
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Abstract
Ultraviolet (UV) radiation is a leading external hazard to the integrity of DNA. Exposure to UV radiation triggers a cascade of chemical reactions, and many molecular products (photolesions) have been isolated that are potentially dangerous for the cellular system. The early steps that take place after UV absorption by DNA have been studied by ultrafast spectroscopy. The review focuses on the evolution of excited electronic states, the formation of photolesions, and processes suppressing their formation. Emphasis is placed on lesions involving two thymine bases, such as the cyclobutane pyrimidine dimer, the (6-4) lesion, and its Dewar valence isomer.
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Affiliation(s)
- Wolfgang J Schreier
- Lehrstuhl für BioMolekulare Optik, Fakultät für Physik and Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, 80538 München, Germany;
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