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Huening KA, Groves JT, Wildenthal JA, Tabita FR, North JA. Escherichia coli possessing the dihydroxyacetone phosphate shunt utilize 5'-deoxynucleosides for growth. Microbiol Spectr 2024; 12:e0308623. [PMID: 38441472 PMCID: PMC10986504 DOI: 10.1128/spectrum.03086-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 02/17/2024] [Indexed: 03/08/2024] Open
Abstract
All organisms utilize S-adenosyl-l-methionine (SAM) as a key co-substrate for the methylation of biological molecules, the synthesis of polyamines, and radical SAM reactions. When these processes occur, 5'-deoxy-nucleosides are formed as byproducts such as S-adenosyl-l-homocysteine, 5'-methylthioadenosine (MTA), and 5'-deoxyadenosine (5dAdo). A prevalent pathway found in bacteria for the metabolism of MTA and 5dAdo is the dihydroxyacetone phosphate (DHAP) shunt, which converts these compounds into dihydroxyacetone phosphate and 2-methylthioacetaldehyde or acetaldehyde, respectively. Previous work in other organisms has shown that the DHAP shunt can enable methionine synthesis from MTA or serve as an MTA and 5dAdo detoxification pathway. Rather, the DHAP shunt in Escherichia coli ATCC 25922, when introduced into E. coli K-12, enables the use of 5dAdo and MTA as a carbon source for growth. When MTA is the substrate, the sulfur component is not significantly recycled back to methionine but rather accumulates as 2-methylthioethanol, which is slowly oxidized non-enzymatically under aerobic conditions. The DHAP shunt in ATCC 25922 is active under oxic and anoxic conditions. Growth using 5-deoxy-d-ribose was observed during aerobic respiration and anaerobic respiration with Trimethylamine N-oxide (TMAO), but not during fermentation or respiration with nitrate. This suggests the DHAP shunt may only be relevant for extraintestinal pathogenic E. coli lineages with the DHAP shunt that inhabit oxic or TMAO-rich extraintestinal environments. This reveals a heretofore overlooked role of the DHAP shunt in carbon and energy metabolism from ubiquitous SAM utilization byproducts and suggests a similar role may occur in other pathogenic and non-pathogenic bacteria with the DHAP shunt. IMPORTANCE The acquisition and utilization of organic compounds that serve as growth substrates are essential for Escherichia coli to grow and multiply. Ubiquitous enzymatic reactions involving S-adenosyl-l-methionine as a co-substrate by all organisms result in the formation of the 5'-deoxy-nucleoside byproducts, 5'-methylthioadenosine and 5'-deoxyadenosine. All E. coli possess a conserved nucleosidase that cleaves these 5'-deoxy-nucleosides into 5-deoxy-pentose sugars for adenine salvage. The DHAP shunt pathway is found in some extraintestinal pathogenic E. coli, but its function in E. coli possessing it has remained unknown. This study reveals that the DHAP shunt enables the utilization of 5'-deoxy-nucleosides and 5-deoxy-pentose sugars as growth substrates in E. coli strains with the pathway during aerobic respiration and anaerobic respiration with TMAO, but not fermentative growth. This provides an insight into the diversity of sugar compounds accessible by E. coli with the DHAP shunt and suggests that the DHAP shunt is primarily relevant in oxic or TMAO-rich extraintestinal environments.
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Affiliation(s)
| | - Joshua T. Groves
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - John A. Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - Justin A. North
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
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2
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Huening KA, Groves JT, Wildenthal JA, Tabita FR, North JA. Utilization of 5'-deoxy-nucleosides as Growth Substrates by Extraintestinal Pathogenic E. coli via the Dihydroxyacetone Phosphate Shunt. bioRxiv 2023:2023.08.10.552779. [PMID: 37609188 PMCID: PMC10441430 DOI: 10.1101/2023.08.10.552779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
All organisms utilize S-adenosyl-l-methionine (SAM) as a key co-substrate for methylation of biological molecules, synthesis of polyamines, and radical SAM reactions. When these processes occur, 5'-deoxy-nucleosides are formed as byproducts such as S-adenosyl-l-homocysteine (SAH), 5'-methylthioadenosine (MTA), and 5'-deoxyadenosine (5dAdo). One of the most prevalent pathways found in bacteria for the metabolism of MTA and 5dAdo is the DHAP shunt, which converts these compounds into dihydroxyacetone phosphate (DHAP) and 2-methylthioacetaldehyde or acetaldehyde, respectively. Previous work has shown that the DHAP shunt can enable methionine synthesis from MTA or serve as an MTA and 5dAdo detoxification pathway. Here we show that in Extraintestinal Pathogenic E. coil (ExPEC), the DHAP shunt serves none of these roles in any significant capacity, but rather physiologically functions as an assimilation pathway for use of MTA and 5dAdo as growth substrates. This is further supported by the observation that when MTA is the substrate for the ExPEC DHAP shunt, the sulfur components is not significantly recycled back to methionine, but rather accumulates as 2-methylthioethanol, which is slowly oxidized non-enzymatically under aerobic conditions. While the pathway is active both aerobically and anaerobically, it only supports aerobic ExPEC growth, suggesting that it primarily functions in oxygenic extraintestinal environments like blood and urine versus the predominantly anoxic gut. This reveals a heretofore overlooked role of the DHAP shunt in carbon assimilation and energy metabolism from ubiquitous SAM utilization byproducts and suggests a similar role may occur in other pathogenic and non-pathogenic bacteria with the DHAP shunt.
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Affiliation(s)
| | - Joshua T. Groves
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| | - John A. Wildenthal
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| | - F. Robert Tabita
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| | - Justin A. North
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
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North JA, Narrowe AB, Xiong W, Byerly KM, Zhao G, Young SJ, Murali S, Wildenthal JA, Cannon WR, Wrighton KC, Hettich RL, Tabita FR. A nitrogenase-like enzyme system catalyzes methionine, ethylene, and methane biogenesis. Science 2020; 369:1094-1098. [PMID: 32855335 DOI: 10.1126/science.abb6310] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 06/12/2020] [Indexed: 12/16/2022]
Abstract
Bacterial production of gaseous hydrocarbons such as ethylene and methane affects soil environments and atmospheric climate. We demonstrate that biogenic methane and ethylene from terrestrial and freshwater bacteria are directly produced by a previously unknown methionine biosynthesis pathway. This pathway, present in numerous species, uses a nitrogenase-like reductase that is distinct from known nitrogenases and nitrogenase-like reductases and specifically functions in C-S bond breakage to reduce ubiquitous and appreciable volatile organic sulfur compounds such as dimethyl sulfide and (2-methylthio)ethanol. Liberated methanethiol serves as the immediate precursor to methionine, while ethylene or methane is released into the environment. Anaerobic ethylene production by this pathway apparently explains the long-standing observation of ethylene accumulation in oxygen-depleted soils. Methane production reveals an additional bacterial pathway distinct from archaeal methanogenesis.
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Affiliation(s)
- Justin A North
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Adrienne B Narrowe
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Weili Xiong
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Kathryn M Byerly
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Guanqi Zhao
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Sarah J Young
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Srividya Murali
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - John A Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - William R Cannon
- Pacific Northwest National Laboratory, Richland, WA 99352, USA.,Department of Mathematics, University of California, Riverside, Riverside, CA 92507, USA
| | - Kelly C Wrighton
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Robert L Hettich
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
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4
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North JA, Wildenthal JA, Erb TJ, Evans BS, Byerly KM, Gerlt JA, Tabita FR. A bifunctional salvage pathway for two distinct S-adenosylmethionine by-products that is widespread in bacteria, including pathogenic Escherichia coli. Mol Microbiol 2020; 113:923-937. [PMID: 31950558 DOI: 10.1111/mmi.14459] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 01/08/2020] [Accepted: 01/12/2020] [Indexed: 01/19/2023]
Abstract
S-adenosyl-l-methionine (SAM) is a necessary cosubstrate for numerous essential enzymatic reactions including protein and nucleotide methylations, secondary metabolite synthesis and radical-mediated processes. Radical SAM enzymes produce 5'-deoxyadenosine, and SAM-dependent enzymes for polyamine, neurotransmitter and quorum sensing compound synthesis produce 5'-methylthioadenosine as by-products. Both are inhibitory and must be addressed by all cells. This work establishes a bifunctional oxygen-independent salvage pathway for 5'-deoxyadenosine and 5'-methylthioadenosine in both Rhodospirillum rubrum and Extraintestinal Pathogenic Escherichia coli. Homologous genes for this pathway are widespread in bacteria, notably pathogenic strains within several families. A phosphorylase (Rhodospirillum rubrum) or separate nucleoside and kinase (Escherichia coli) followed by an isomerase and aldolase sequentially function to salvage these two wasteful and inhibitory compounds into adenine, dihydroxyacetone phosphate and acetaldehyde or (2-methylthio)acetaldehyde during both aerobic and anaerobic growth. Both SAM by-products are metabolized with equal affinity during aerobic and anaerobic growth conditions, suggesting that the dual-purpose salvage pathway plays a central role in numerous environments, notably the human body during infection. Our newly discovered bifunctional oxygen-independent pathway, widespread in bacteria, salvages at least two by-products of SAM-dependent enzymes for carbon and sulfur salvage, contributing to cell growth.
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Affiliation(s)
- Justin A North
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - John A Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - Tobias J Erb
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Bradley S Evans
- The Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Kathryn M Byerly
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - John A Gerlt
- Department of Biochemistry, The Institute for Genomic Biology, Champaign, IL, USA.,Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Fred R Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
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Satagopan S, North JA, Arbing MA, Varaljay VA, Haines SN, Wildenthal JA, Byerly KM, Shin A, Tabita FR. Structural Perturbations of Rhodopseudomonas palustris Form II RuBisCO Mutant Enzymes That Affect CO2 Fixation. Biochemistry 2019; 58:3880-3892. [DOI: 10.1021/acs.biochem.9b00617] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Sriram Satagopan
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Justin A. North
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Mark A. Arbing
- UCLA-DOE Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Vanessa A. Varaljay
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Sidney N. Haines
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - John A. Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Kathryn M. Byerly
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Annie Shin
- UCLA-DOE Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
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North JA, Miller AR, Wildenthal JA, Young SJ, Tabita FR. Microbial pathway for anaerobic 5'-methylthioadenosine metabolism coupled to ethylene formation. Proc Natl Acad Sci U S A 2017; 114:E10455-E10464. [PMID: 29133429 PMCID: PMC5715764 DOI: 10.1073/pnas.1711625114] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Numerous cellular processes involving S-adenosyl-l-methionine result in the formation of the toxic by-product, 5'-methylthioadenosine (MTA). To prevent inhibitory MTA accumulation and retain biologically available sulfur, most organisms possess the "universal" methionine salvage pathway (MSP). However, the universal MSP is inherently aerobic due to a requirement of molecular oxygen for one of the key enzymes. Here, we report the presence of an exclusively anaerobic MSP that couples MTA metabolism to ethylene formation in the phototrophic bacteria Rhodospirillum rubrum and Rhodopseudomonas palustris In vivo metabolite analysis of gene deletion strains demonstrated that this anaerobic MSP functions via sequential action of MTA phosphorylase (MtnP), 5-(methylthio)ribose-1-phosphate isomerase (MtnA), and an annotated class II aldolase-like protein (Ald2) to form 2-(methylthio)acetaldehyde as an intermediate. 2-(Methylthio)acetaldehyde is reduced to 2-(methylthio)ethanol, which is further metabolized as a usable organic sulfur source, generating stoichiometric amounts of ethylene in the process. Ethylene induction experiments using 2-(methylthio)ethanol versus sulfate as sulfur sources further indicate anaerobic ethylene production from 2-(methylthio)ethanol requires protein synthesis and that this process is regulated. Finally, phylogenetic analysis reveals that the genes corresponding to these enzymes, and presumably the pathway, are widespread among anaerobic and facultatively anaerobic bacteria from soil and freshwater environments. These results not only establish the existence of a functional, exclusively anaerobic MSP, but they also suggest a possible route by which ethylene is produced by microbes in anoxic environments.
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Affiliation(s)
- Justin A North
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - Anthony R Miller
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - John A Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - Sarah J Young
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
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Teeling-Smith RM, Jung YW, Scozzaro N, Cardellino J, Rampersaud I, North JA, Šimon M, Bhallamudi VP, Rampersaud A, Johnston-Halperin E, Poirier MG, Hammel PC. Electron Paramagnetic Resonance of a Single NV Nanodiamond Attached to an Individual Biomolecule. Biophys J 2017; 110:2044-52. [PMID: 27166812 DOI: 10.1016/j.bpj.2016.03.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/19/2016] [Accepted: 03/07/2016] [Indexed: 11/26/2022] Open
Abstract
Electron paramagnetic resonance (EPR), an established and powerful methodology for studying atomic-scale biomolecular structure and dynamics, typically requires in excess of 10(12) labeled biomolecules. Single-molecule measurements provide improved insights into heterogeneous behaviors that can be masked in ensemble measurements and are often essential for illuminating the molecular mechanisms behind the function of a biomolecule. Here, we report EPR measurements of a single labeled biomolecule. We selectively label an individual double-stranded DNA molecule with a single nanodiamond containing nitrogen-vacancy centers, and optically detect the paramagnetic resonance of nitrogen-vacancy spins in the nanodiamond probe. Analysis of the spectrum reveals that the nanodiamond probe has complete rotational freedom and that the characteristic timescale for reorientation of the nanodiamond probe is slow compared with the transverse spin relaxation time. This demonstration of EPR spectroscopy of a single nanodiamond-labeled DNA provides the foundation for the development of single-molecule magnetic resonance studies of complex biomolecular systems.
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Affiliation(s)
| | - Young Woo Jung
- Samsung Electronics, San #24 Nongseo-Dong, Giheung-Gu, Yongin-City, Gyonggi-Do, Korea
| | - Nicolas Scozzaro
- Department of Physics, The Ohio State University, Columbus, Ohio
| | | | | | - Justin A North
- Department of Physics, The Ohio State University, Columbus, Ohio
| | - Marek Šimon
- Department of Physics, The Ohio State University, Columbus, Ohio
| | | | | | | | | | - P Chris Hammel
- Department of Physics, The Ohio State University, Columbus, Ohio.
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Varaljay VA, Satagopan S, North JA, Witte B, Dourado MN, Anantharaman K, Arbing MA, McCann SH, Oremland RS, Banfield JF, Wrighton KC, Tabita FR. Functional metagenomic selection of ribulose 1, 5-bisphosphate carboxylase/oxygenase from uncultivated bacteria. Environ Microbiol 2016; 18:1187-99. [PMID: 26617072 PMCID: PMC10035430 DOI: 10.1111/1462-2920.13138] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/17/2015] [Accepted: 11/17/2015] [Indexed: 01/29/2023]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a critical yet severely inefficient enzyme that catalyses the fixation of virtually all of the carbon found on Earth. Here, we report a functional metagenomic selection that recovers physiologically active RubisCO molecules directly from uncultivated and largely unknown members of natural microbial communities. Selection is based on CO2 -dependent growth in a host strain capable of expressing environmental deoxyribonucleic acid (DNA), precluding the need for pure cultures or screening of recombinant clones for enzymatic activity. Seventeen functional RubisCO-encoded sequences were selected using DNA extracted from soil and river autotrophic enrichments, a photosynthetic biofilm and a subsurface groundwater aquifer. Notably, three related form II RubisCOs were recovered which share high sequence similarity with metagenomic scaffolds from uncultivated members of the Gallionellaceae family. One of the Gallionellaceae RubisCOs was purified and shown to possess CO2 /O2 specificity typical of form II enzymes. X-ray crystallography determined that this enzyme is a hexamer, only the second form II multimer ever solved and the first RubisCO structure obtained from an uncultivated bacterium. Functional metagenomic selection leverages natural biological diversity and billions of years of evolution inherent in environmental communities, providing a new window into the discovery of CO2 -fixing enzymes not previously characterized.
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Affiliation(s)
- Vanessa A. Varaljay
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Sriram Satagopan
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Justin A. North
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Brian Witte
- The Botanical Research Institute of Texas, Fort Worth, TX 76107, USA
| | | | - Karthik Anantharaman
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| | - Mark A. Arbing
- Protein Expression Technology Center, UCLA-DOE Institute, University of California, Los Angeles, CA 90095, USA
| | | | | | - Jillian F. Banfield
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| | - Kelly C. Wrighton
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
- For correspondence. ; Tel. +1 614 292 4297; Fax: +1 614 292 6337
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Dey S, North JA, Sriram J, Evans BS, Tabita FR. In Vivo Studies in Rhodospirillum rubrum Indicate That Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) Catalyzes Two Obligatorily Required and Physiologically Significant Reactions for Distinct Carbon and Sulfur Metabolic Pathways. J Biol Chem 2015; 290:30658-68. [PMID: 26511314 DOI: 10.1074/jbc.m115.691295] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Indexed: 12/19/2022] Open
Abstract
All organisms possess fundamental metabolic pathways to ensure that needed carbon and sulfur compounds are provided to the cell in the proper chemical form and oxidation state. For most organisms capable of using CO2 as sole source of carbon, ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes primary carbon dioxide assimilation. In addition, sulfur salvage pathways are necessary to ensure that key sulfur-containing compounds are both available and, where necessary, detoxified in the cell. Using knock-out mutations and metabolomics in the bacterium Rhodospirillum rubrum, we show here that Rubisco concurrently catalyzes key and essential reactions for seemingly unrelated but physiologically essential central carbon and sulfur salvage metabolic pathways of the cell. In this study, complementation and mutagenesis studies indicated that representatives of all known extant functional Rubisco forms found in nature are capable of simultaneously catalyzing reactions required for both CO2-dependent growth as well as growth using 5-methylthioadenosine as sole sulfur source under anaerobic photosynthetic conditions. Moreover, specific inactivation of the CO2 fixation reaction did not affect the ability of Rubisco to support anaerobic 5-methylthioadenosine metabolism, suggesting that the active site of Rubisco has evolved to ensure that this enzyme maintains both key functions. Thus, despite the coevolution of both functions, the active site of this protein may be differentially modified to affect only one of its key functions.
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Affiliation(s)
- Swati Dey
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Justin A North
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Jaya Sriram
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Bradley S Evans
- the Donald Danforth Plant Science Center, St. Louis, Missouri, 63132
| | - F Robert Tabita
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
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Affiliation(s)
- A A Spector
- Department of Biochemistry, College of Medicine, University of Iowa, Iowa City
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Luo Y, North JA, Poirier MG. Single molecule fluorescence methodologies for investigating transcription factor binding kinetics to nucleosomes and DNA. Methods 2014; 70:108-18. [PMID: 25304387 DOI: 10.1016/j.ymeth.2014.09.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 09/03/2014] [Accepted: 09/30/2014] [Indexed: 11/20/2022] Open
Abstract
Site specific DNA binding complexes must bind their DNA target sites and then reside there for a sufficient amount of time for proper regulation of DNA processing including transcription, replication and DNA repair. In eukaryotes, the occupancy of DNA binding complexes at their target sites is regulated by chromatin structure and dynamics. Methodologies that probe both the binding and dissociation kinetics of DNA binding proteins with naked and nucleosomal DNA are essential for understanding the mechanisms by which these complexes function. Here, we describe single-molecule fluorescence methodologies for quantifying the binding and dissociation kinetics of transcription factors at a target site within DNA, nucleosomes and nucleosome arrays. This approach allowed for the unexpected observation that nucleosomes impact not only binding but also dissociation kinetics of transcription factors and is well-suited for the investigation of numerous DNA processing complexes that directly interact with DNA organized into chromatin.
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Affiliation(s)
- Yi Luo
- Department of Physics, The Ohio State University, Columbus, OH 43210-1117, United States; Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210-1117, United States
| | - Justin A North
- Department of Physics, The Ohio State University, Columbus, OH 43210-1117, United States
| | - Michael G Poirier
- Department of Physics, The Ohio State University, Columbus, OH 43210-1117, United States; Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210-1117, United States.
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Musselman CA, Gibson MD, Hartwick EW, North JA, Gatchalian J, Poirier MG, Kutateladze TG. Binding of PHF1 Tudor to H3K36me3 enhances nucleosome accessibility. Nat Commun 2014; 4:2969. [PMID: 24352064 PMCID: PMC4007151 DOI: 10.1038/ncomms3969] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 11/18/2013] [Indexed: 01/15/2023] Open
Abstract
The Tudor domain of human PHF1 recognizes trimethylated lysine 36 of histone H3 (H3K36me3). This interaction modulates methyltransferase activity of the PRC2 complex and plays a role in retention of PHF1 at the DNA damage sites. We have previously determined the structural basis for the association of Tudor with a methylated histone peptide. Here we detail the molecular mechanism of binding of the Tudor domain to the H3KC36me3-nucleosome core particle (H3KC36me3-NCP). Using a combination of TROSY NMR and FRET we show that Tudor concomitantly interacts with H3K36me3 and DNA. Binding of the PHF1 Tudor domain to the H3KC36me3-NCP stabilizes the nucleosome in a conformation in which the nucleosomal DNA is more accessible to DNA-binding regulatory proteins. Our data provide a mechanistic explanation for the consequence of reading of the active mark H3K36me3 by the PHF1 Tudor domain.
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Affiliation(s)
- Catherine A Musselman
- 1] Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA [2]
| | - Matthew D Gibson
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - Erik W Hartwick
- Program in Structural Biology and Biochemistry, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Justin A North
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - Jovylyn Gatchalian
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Michael G Poirier
- Department of Physics, Ohio State University, Columbus, Ohio 43210, USA
| | - Tatiana G Kutateladze
- 1] Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA [2] Program in Structural Biology and Biochemistry, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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North JA, Šimon M, Ferdinand MB, Shoffner MA, Picking JW, Howard CJ, Mooney AM, van Noort J, Poirier MG, Ottesen JJ. Histone H3 phosphorylation near the nucleosome dyad alters chromatin structure. Nucleic Acids Res 2014; 42:4922-33. [PMID: 24561803 PMCID: PMC4005658 DOI: 10.1093/nar/gku150] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Nucleosomes contain ∼146 bp of DNA wrapped around a histone protein octamer that controls DNA accessibility to transcription and repair complexes. Posttranslational modification (PTM) of histone proteins regulates nucleosome function. To date, only modest changes in nucleosome structure have been directly attributed to histone PTMs. Histone residue H3(T118) is located near the nucleosome dyad and can be phosphorylated. This PTM destabilizes nucleosomes and is implicated in the regulation of transcription and repair. Here, we report gel electrophoretic mobility, sucrose gradient sedimentation, thermal disassembly, micrococcal nuclease digestion and atomic force microscopy measurements of two DNA–histone complexes that are structurally distinct from nucleosomes. We find that H3(T118ph) facilitates the formation of a nucleosome duplex with two DNA molecules wrapped around two histone octamers, and an altosome complex that contains one DNA molecule wrapped around two histone octamers. The nucleosome duplex complex forms within short ∼150 bp DNA molecules, whereas altosomes require at least ∼250 bp of DNA and form repeatedly along 3000 bp DNA molecules. These results are the first report of a histone PTM significantly altering the nucleosome structure.
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Affiliation(s)
- Justin A North
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA and Huygens-Kamerlingh Onnes Laboratory, Leiden University, The Netherlands
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14
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Abstract
Transcription factors (TF) bind DNA-target sites within promoters to activate gene expression. TFs target their DNA-recognition sequences with high specificity by binding with resident times of up to hours in vitro. However, in vivo TFs can exchange on the order of seconds. The factors that regulate TF dynamics in vivo and increase dissociation rates by orders of magnitude are not known. We investigated TF binding and dissociation dynamics at their recognition sequence within duplex DNA, single nucleosomes and short nucleosome arrays with single molecule total internal reflection fluorescence (smTIRF) microscopy. We find that the rate of TF dissociation from its site within either nucleosomes or nucleosome arrays is increased by 1000-fold relative to duplex DNA. Our results suggest that TF binding within chromatin could be responsible for the dramatic increase in TF exchange in vivo. Furthermore, these studies demonstrate that nucleosomes regulate DNA–protein interactions not only by preventing DNA–protein binding but by dramatically increasing the dissociation rate of protein complexes from their DNA-binding sites.
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Affiliation(s)
- Yi Luo
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA and Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
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15
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Gao M, Nadaud PS, Bernier MW, North JA, Hammel PC, Poirier MG, Jaroniec CP. Histone H3 and H4 N-terminal tails in nucleosome arrays at cellular concentrations probed by magic angle spinning NMR spectroscopy. J Am Chem Soc 2013; 135:15278-81. [PMID: 24088044 DOI: 10.1021/ja407526s] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chromatin is a supramolecular assembly of DNA and histone proteins, organized into nucleosome repeat units. The dynamics of chromatin organization regulates DNA accessibility to eukaryotic transcription and DNA repair complexes. Yet, the structural and dynamic properties of chromatin at high concentrations characteristic of the cellular environment (>∼200 mg/mL) are largely unexplored at the molecular level. Here, we apply MAS NMR to directly probe the dynamic histone protein regions in (13)C,(15)N-enriched recombinant nucleosome arrays at cellular chromatin concentrations and conditions designed to emulate distinct states of DNA condensation, with focus on the flexible H3 and H4 N-terminal tails which mediate chromatin compaction. 2D (1)H-(13)C and (1)H-(15)N spectra reveal numerous correlations for H3 and H4 backbone and side-chain atoms, enabling identification of specific residues making up the dynamically disordered N-terminal tail domains. Remarkably, we find that both the H3 and H4 N-terminal tails are overall dynamic even in a highly condensed state. This significant conformational flexibility of the histone tails suggests that they remain available for protein binding in compact chromatin states to enable regulation of heterochromatin. Furthermore, our study provides a foundation for quantitative structural and dynamic investigations of chromatin at physiological concentrations.
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Affiliation(s)
- Min Gao
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
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16
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Abstract
Double-strand breaks (DSB) occur in chromatin following replication fork collapse and chemical or physical damage [Symington and Gautier (Double-strand break end resection and repair pathway choice. Annu. Rev. Genet. 2011;45:247–271.)] and may be repaired by homologous recombination (HR) and non-homologous end-joining. Nucleosomes are the fundamental units of chromatin and must be remodeled during DSB repair by HR [Andrews and Luger (Nucleosome structure(s) and stability: variations on a theme. Annu. Rev. Biophys. 2011;40:99–117.)]. Physical initiation of HR requires RAD51, which forms a nucleoprotein filament (NPF) that catalyzes homologous pairing and strand exchange (recombinase) between DNAs that ultimately bridges the DSB gap [San Filippo, Sung and Klein. (Mechanism of eukaryotic HR. Annu. Rev. Biochem. 2008;77:229–257.)]. RAD51 forms an NPF on single-stranded DNA and double-stranded DNA (dsDNA). Although the single-stranded DNA NPF is essential for recombinase initiation, the role of the dsDNA NPF is less clear. Here, we demonstrate that the human RAD51 (HsRAD51) dsDNA NPF disassembles nucleosomes by unwrapping the DNA from the core histones. HsRAD51 that has been constitutively or biochemically activated for recombinase functions displays significantly reduced nucleosome disassembly activity. These results suggest that HsRAD51 can perform ATP hydrolysis-dependent nucleosome disassembly in addition to its recombinase functions.
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Affiliation(s)
- Justin A North
- Department of Physics, The Ohio State University, Columbus OH 43210, USA, Molecular Virology, Immunology and Medical Genetics, The Ohio State University Medical Center, Columbus, OH 43210, USA, Chemistry and Biochemistry Department, The Ohio State University, Columbus OH 43210, USA and Human Cancer Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
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17
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Eidahl JO, Crowe BL, North JA, McKee CJ, Shkriabai N, Feng L, Plumb M, Graham RL, Gorelick RJ, Hess S, Poirier MG, Foster MP, Kvaratskhelia M. Structural basis for high-affinity binding of LEDGF PWWP to mononucleosomes. Nucleic Acids Res 2013; 41:3924-36. [PMID: 23396443 PMCID: PMC3616739 DOI: 10.1093/nar/gkt074] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 12/27/2012] [Accepted: 01/18/2013] [Indexed: 01/19/2023] Open
Abstract
Lens epithelium-derived growth factor (LEDGF/p75) tethers lentiviral preintegration complexes (PICs) to chromatin and is essential for effective HIV-1 replication. LEDGF/p75 interactions with lentiviral integrases are well characterized, but the structural basis for how LEDGF/p75 engages chromatin is unknown. We demonstrate that cellular LEDGF/p75 is tightly bound to mononucleosomes (MNs). Our proteomic experiments indicate that this interaction is direct and not mediated by other cellular factors. We determined the solution structure of LEDGF PWWP and monitored binding to the histone H3 tail containing trimethylated Lys36 (H3K36me3) and DNA by NMR. Results reveal two distinct functional interfaces of LEDGF PWWP: a well-defined hydrophobic cavity, which selectively interacts with the H3K36me3 peptide and adjacent basic surface, which non-specifically binds DNA. LEDGF PWWP exhibits nanomolar binding affinity to purified native MNs, but displays markedly lower affinities for the isolated H3K36me3 peptide and DNA. Furthermore, we show that LEDGF PWWP preferentially and tightly binds to in vitro reconstituted MNs containing a tri-methyl-lysine analogue at position 36 of H3 and not to their unmodified counterparts. We conclude that cooperative binding of the hydrophobic cavity and basic surface to the cognate histone peptide and DNA wrapped in MNs is essential for high-affinity binding to chromatin.
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Affiliation(s)
- Jocelyn O. Eidahl
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Brandon L. Crowe
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Justin A. North
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Christopher J. McKee
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Nikoloz Shkriabai
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Lei Feng
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Matthew Plumb
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Robert L. Graham
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Robert J. Gorelick
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Sonja Hess
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Michael G. Poirier
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Mark P. Foster
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Mamuka Kvaratskhelia
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA and AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
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18
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North JA, Shimko JC, Javaid S, Mooney AM, Shoffner MA, Rose SD, Bundschuh R, Fishel R, Ottesen JJ, Poirier MG. Regulation of the nucleosome unwrapping rate controls DNA accessibility. Nucleic Acids Res 2012; 40:10215-27. [PMID: 22965129 PMCID: PMC3488218 DOI: 10.1093/nar/gks747] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic genomes are repetitively wrapped into nucleosomes that then regulate access of transcription and DNA repair complexes to DNA. The mechanisms that regulate extrinsic protein interactions within nucleosomes are unresolved. We demonstrate that modulation of the nucleosome unwrapping rate regulates protein binding within nucleosomes. Histone H3 acetyl-lysine 56 [H3(K56ac)] and DNA sequence within the nucleosome entry-exit region additively influence nucleosomal DNA accessibility by increasing the unwrapping rate without impacting rewrapping. These combined epigenetic and genetic factors influence transcription factor (TF) occupancy within the nucleosome by at least one order of magnitude and enhance nucleosome disassembly by the DNA mismatch repair complex, hMSH2-hMSH6. Our results combined with the observation that ∼30% of Saccharomyces cerevisiae TF-binding sites reside in the nucleosome entry-exit region suggest that modulation of nucleosome unwrapping is a mechanism for regulating transcription and DNA repair.
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Affiliation(s)
- Justin A North
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA
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19
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Chen A, Vieira G, Henighan T, Howdyshell M, North JA, Hauser AJ, Yang FY, Poirier MG, Jayaprakash C, Sooryakumar R. Regulating Brownian fluctuations with tunable microscopic magnetic traps. Phys Rev Lett 2011; 107:087206. [PMID: 21929204 PMCID: PMC3896074 DOI: 10.1103/physrevlett.107.087206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Indexed: 05/15/2023]
Abstract
A major challenge to achieving positional control of fluid borne submicron sized objects is regulating their Brownian fluctuations. We present a magnetic-field-based trap that regulates the thermal fluctuations of superparamagnetic beads in suspension. Local domain-wall fields originating from patterned magnetic wires, whose strength and profile are tuned by weak external fields, enable the bead trajectories within the trap to be managed and easily varied between strong confinements and delocalized spatial excursions that are described remarkably well by simulations.
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Affiliation(s)
- A Chen
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
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20
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Abstract
The expression, replication and repair of eukaryotic genomes require the fundamental organizing unit of chromatin, the nucleosome, to be unwrapped and disassembled. We have developed a quantitative model of nucleosome dynamics which provides a fundamental understanding of these DNA processes. We calibrated this model using results from high precision single molecule nucleosome unzipping experiments, and then tested its predictions for experiments in which nucleosomes are disassembled by the DNA mismatch recognition complex hMSH2-hMSH6. We found that this calibrated model quantitatively describes hMSH2-hMSH6 induced disassembly rates of nucleosomes with two separate DNA sequences and four distinct histone modification states. In addition, this model provides mechanistic insight into nucleosome disassembly by hMSH2-hMSH6 and the influence of histone modifications on this disassembly reaction. This model's precise agreement with current experiments suggests that it can be applied more generally to provide important mechanistic understanding of the numerous nucleosome alterations that occur during DNA processing.
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Affiliation(s)
- Robert A Forties
- Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210-1117, USA
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21
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North JA, Javaid S, Ferdinand MB, Chatterjee N, Picking JW, Shoffner M, Nakkula RJ, Bartholomew B, Ottesen JJ, Fishel R, Poirier MG. Phosphorylation of histone H3(T118) alters nucleosome dynamics and remodeling. Nucleic Acids Res 2011; 39:6465-74. [PMID: 21576235 PMCID: PMC3159469 DOI: 10.1093/nar/gkr304] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Nucleosomes, the fundamental units of chromatin structure, are regulators and barriers to transcription, replication and repair. Post-translational modifications (PTMs) of the histone proteins within nucleosomes regulate these DNA processes. Histone H3(T118) is a site of phosphorylation [H3(T118ph)] and is implicated in regulation of transcription and DNA repair. We prepared H3(T118ph) by expressed protein ligation and determined its influence on nucleosome dynamics. We find H3(T118ph) reduces DNA-histone binding by 2 kcal/mol, increases nucleosome mobility by 28-fold and increases DNA accessibility near the dyad region by 6-fold. Moreover, H3(T118ph) increases the rate of hMSH2-hMSH6 nucleosome disassembly and enables nucleosome disassembly by the SWI/SNF chromatin remodeler. These studies suggest that H3(T118ph) directly enhances and may reprogram chromatin remodeling reactions.
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Affiliation(s)
- Justin A North
- Department of Physics, The Ohio State University and The Ohio State University Medical Center, Columbus, OH 43210, USA
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22
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Abstract
Twenty-six commercially available parent training manuals were surveyed with the goal of providing helpful information to the professional for selection of manuals. Included were manuals for parents as well as manuals for professionals for use in conducting individual or group treatment. The following information was given for all manuals: the characteristics of the target populations for whom the manuals were intended, readability levels, use made of technical language, provision of glossary, organization and format of the book, availability of supplementary materials such as leaders' guides, and references to reviews by other authors. In an additional section, the research literature dealing with evaluation of these manuals was reviewed and summarized as a means of acquainting the reader with the available scientific information on their effectiveness. A report on the status of each manual in terms of evaluation was provided in tabular form. The evaluation of manuals by conduct of empirical research to determine their usefulness to the consumer was emphasized.
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Manohar M, Mooney AM, North JA, Nakkula RJ, Picking JW, Edon A, Fishel R, Poirier MG, Ottesen JJ. Acetylation of histone H3 at the nucleosome dyad alters DNA-histone binding. J Biol Chem 2009; 284:23312-21. [PMID: 19520870 DOI: 10.1074/jbc.m109.003202] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Histone post-translational modifications are essential for regulating and facilitating biological processes such as RNA transcription and DNA repair. Fifteen modifications are located in the DNA-histone dyad interface and include the acetylation of H3-K115 (H3-K115Ac) and H3-K122 (H3-K122Ac), but the functional consequences of these modifications are unknown. We have prepared semisynthetic histone H3 acetylated at Lys-115 and/or Lys-122 by expressed protein ligation and incorporated them into single nucleosomes. Competitive reconstitution analysis demonstrated that the acetylation of H3-K115 and H3-K122 reduces the free energy of histone octamer binding. Restriction enzyme kinetic analysis suggests that these histone modifications do not alter DNA accessibility near the sites of modification. However, acetylation of H3-K122 increases the rate of thermal repositioning. Remarkably, Lys --> Gln substitution mutations, which are used to mimic Lys acetylation, do not fully duplicate the effects of the H3-K115Ac or H3-K122Ac modifications. Our results are consistent with the conclusion that acetylation in the dyad interface reduces DNA-histone interaction(s), which may facilitate nucleosome repositioning and/or assembly/disassembly.
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Affiliation(s)
- Mridula Manohar
- Department of Biochemistry, Ohio State University, Columbus, Ohio 43210, USA
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24
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Abstract
A practical method has been developed for obtaining partial Stokes vector (IQU_) and derivative (IPT_) images of the polarized sky-dome. This method takes advantage of a four-lens stereoscopic camera, a dome mirror, photo CD processing, and commercially available digital image-processing software.
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Affiliation(s)
- J A North
- Central Imagery Office, 8401 Old Courthouse Road, Vienna, Virginia 22181, USA
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25
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Abstract
Protection by antioxidant nutrients against oxidative damage in rat heart homogenates was studied. Following spontaneous oxidation of heart homogenates from rats fed vitamin E, selenium, or beta-carotene, oxidized heme proteins (OHP) and thiobarbituric acid reactive substances (TBARS) were measured. The absorbance spectra of oxidized and reduced heme proteins were analyzed with a heme spectral analysis program (HSAP) developed in this laboratory. HSAP is a multicomponent analysis program that uses successive approximations and computer spread-sheet solver functions to deconvolute a complex absorbance spectrum into individual heme protein spectra. Vitamin E markedly decreased formation of OHP, and vitamin E, selenium, or beta-carotene significantly lowered the production of TBARS during spontaneous oxidation of heart homogenates compared with homogenates from rats fed antioxidant-deficient diets. Pyridine hemochrome analysis showed that the total amounts of heme proteins present in the homogenates decreased during the oxidative incubation period. The formation of OHP correlated significantly with the amount of TBARS produced and could be simulated as a function of the oxidative and protective reactions involved in the oxidation of rat heart homogenates.
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Affiliation(s)
- J A North
- Department of Food Science and Technology, University of California, Davis 95616, USA
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26
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Abstract
Absorption spectra of heme proteins in a tissue homogenate contain information about the oxidation status of the biological sample. Deconvolution of absorption spectra can be used to quantitate the amount of individual heme proteins present in the mixture. The heme spectral analysis program (HSAP), a computer spreadsheet program, was used to quantitatively calculate values for heme proteins measured spectrally (390 to 450 and 500 to 640 nm) in tissue homogenates undergoing oxidation. The amount of oxidized heme proteins obtained by HSAP can be compared to other measurements of tissue oxidation. Precise quantitation of the amount of heme proteins present in a homogenate sample provided accurate assessment of the oxidized heme proteins calculated by HSAP. This quantitation was achieved through modification of existing pyridine hemochrome methods. Input into HSAP of the total heme protein content via the pyridine hemochrome value generated reproducible values for oxidized heme proteins. The program has broad potential as a multicomponent analysis tool. Modification of HSAP led to the development of a difference spectra analysis program (DSAP) which was used to quantitate the type and amount of heme proteins observed in mitochondrial difference spectra. In the present application, HSAP and DSAP provide methods for interpreting complex spectral information of multicomponent biological samples that undergo oxidation.
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Affiliation(s)
- J A North
- Department of Food Science and Technology, University of California, Davis 95616, USA
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27
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Abstract
The effect of antioxidant nutrients in rat kidney homogenates was studied by measuring the formation of oxidized heme proteins (OHP) and thiobarbituric acid reactive substances (TBARS) during spontaneous oxidation at 37 degrees. OHP were analyzed using a modified spreadsheet protocol; the Heme Protein Spectra Analysis Program (HPSAP). Male Sprague-Dawley (SD) rats were fed a basal diet fortified with vitamin E, selenium, or beta-carotene, or a combination of all three antioxidants. A second group of male SD rats received a basal diet fortified with Trolox, ascorbic acid palmitate, acetylcysteine, beta-carotene, coenzyme Q10, coenzyme Q0, and (+)-catechin. A control group of rats was given a vitamin E- and selenium-deficient basal diet. The amount of TBARS production during a 1 h reaction decreased as the relative antioxidant effectiveness of the dietary treatments increased. Dietary treatments providing nine antioxidants significantly reduced the formation of OHP and methemoglobin during the 1 h reaction compared to the dietary treatment providing only two antioxidant nutrients. These data suggest that increasing the diversity and quantity of antioxidants in the diet provides significantly more protection for heme proteins and lipids in kidney tissue than individual antioxidants or a combination of vitamin E and selenium.
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Affiliation(s)
- C A Knudsen
- Department of Food Science and Technology, University of California, Davis 95616, USA
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28
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Alexander-North LS, North JA, Kiminyo KP, Buettner GR, Spector AA. Polyunsaturated fatty acids increase lipid radical formation induced by oxidant stress in endothelial cells. J Lipid Res 1994; 35:1773-85. [PMID: 7852854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Lipid-derived free radicals were detected by electron paramagnetic resonance (EPR) spectrometry when cultured endothelial cells attached to Cytodex beads were exposed to iron-induced oxidant stress in the presence of the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN). Radical adduct formation was enhanced greatly when the cells were supplemented during growth with polyunsaturated fatty acids. The largest EPR signal intensity was observed in cells enriched with docosahexaenoic acid (DHA) or eicosapentaenoic acid, but enhanced radical adduct production also occurred after exposure to arachidonic, alpha-linolenic, gamma-linolenic, or linoleic acids. Radical adduct formation increased as the DHA content of the cells increased and approached a maximum after only 6 h of exposure to DHA. Ascorbic acid, acting as a pro-oxidant, enhanced radical adduct formation in cells enriched with DHA. The EPR signal intensity was reduced when the cells were tested 6 h after replacement of the DHA-enriched medium with a medium containing 5-20 microM oleic acid, indicating that the increased endothelial responsiveness to oxidant stress is reversible. Likewise, when U937 monocytes enriched with DHA were exposed subsequently to 20 microM oleic acid, a 35-45% decrease in radical adduct formation also occurred. These findings suggest that the endothelium may become more susceptible to oxidative injury when it is exposed to elevated amounts of polyunsaturated fatty acids. However, the effect appears to be temporary. The protective action of oleic acid against oxidant stress is not confined to the endothelium; it applies to monocytes as well.
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Affiliation(s)
- L S Alexander-North
- Department of Biochemistry, College of Medicine, University of Iowa, Iowa City 52242
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Alexander-North LS, North JA, Kiminyo KP, Buettner GR, Spector AA. Polyunsaturated fatty acids increase lipid radical formation induced by oxidant stress in endothelial cells. J Lipid Res 1994. [DOI: 10.1016/s0022-2275(20)39772-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
Lipid-derived free radicals generated from intact human U937 monocytes exposed to iron-induced oxidative stress were detected by electron paramagnetic resonance (EPR) with the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN). Lipid radical formation was enhanced when the cells were enriched with n-3 or n-6 polyunsaturated fatty acids. Computer simulation indicated that at least two POBN spin adducts were formed, having spectral characteristics consistent with carbon-centered radicals (aN = 15.9 G and aH = 2.6 G; aN = 15.1 G and aH = 2.8 G). These alkyl radicals are probably formed by beta-scission of alkoxyl radicals. POBN spin adduct formation correlated with ethane generation. Addition of ascorbate to the assay medium greatly increased the radical signal intensity. Although radical generation was cell dependent and POBN spin adducts were observed in cell homogenates, the adducts formed by the intact cells were detected only in the extracellular medium. These findings indicate that the extent of lipid radical formation in response to oxidative stress can be influenced by changes in the polyunsaturated fatty acid composition of the cell lipids and suggest the possibility that carbon-centered lipi radicals may interact with extracellular structures.
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Affiliation(s)
- J A North
- Department of Biochemistry, College of Medicine, University of Iowa, Iowa City 52242
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Weber ND, Andersen DO, North JA, Murray BK, Lawson LD, Hughes BG. In vitro virucidal effects of Allium sativum (garlic) extract and compounds. Planta Med 1992; 58:417-23. [PMID: 1470664 DOI: 10.1055/s-2006-961504] [Citation(s) in RCA: 153] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Garlic (Allium sativum) has been shown to have antiviral activity, but the compounds responsible have not been identified. Using direct pre-infection incubation assays, we determined the in vitro virucidal effects of fresh garlic extract, its polar fraction, and the following garlic associated compounds: diallyl thiosulfinate (allicin), allyl methyl thiosulfinate, methyl allyl thiosulfinate, ajoene, alliin, deoxyalliin, diallyl disulfide, and diallyl trisulfide. Activity was determined against selected viruses including, herpes simplex virus type 1, herpes simplex virus type 2, parainfluenza virus type 3, vaccinia virus, vesicular stomatitis virus, and human rhinovirus type 2. The order for virucidal activity generally was: ajoene > allicin > allyl methyl thiosulfinate > methyl allyl thiosulfinate. Ajoene was found in oil-macerates of garlic but not in fresh garlic extracts. No activity was found for the garlic polar fraction, alliin, deoxyalliin, diallyl disulfide, or diallyl trisulfide. Fresh garlic extract, in which thiosulfinates appeared to be the active components, was virucidal to each virus tested. The predominant thiosulfinate in fresh garlic extract was allicin. Lack of reduction in yields of infectious virus indicated undetectable levels of intracellular antiviral activity for either allicin or fresh garlic extract. Furthermore, concentrations that were virucidal were also toxic to HeLa and Vero cells. Virucidal assay results were not influenced by cytotoxicity since the compounds were diluted below toxic levels prior to assaying for infectious virus. These results indicate that virucidal activity and cytotoxicity may have depended upon the viral envelope and cell membrane, respectively. However, activity against non-enveloped virus may have been due to inhibition of viral adsorption or penetration.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N D Weber
- Department of Microbiology, Brigham Young University, Provo, Utah 84602
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North JA, Spector AA, Buettner GR. Detection of lipid radicals by electron paramagnetic resonance spin trapping using intact cells enriched with polyunsaturated fatty acid. J Biol Chem 1992; 267:5743-6. [PMID: 1313417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Electron paramagnetic resonance (EPR) spin trapping was used to detect lipid-derived free radicals generated by iron-induced oxidative stress in intact cells. Using the spin trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (POBN), carbon-centered radical adducts were detected. These lipid-derived free radicals were formed during incubation of ferrous iron with U937 cells that were enriched with docosahexaenoic acid (22:6n-3). The EPR spectra exhibited apparent hyperfine splittings characteristic of a POBN/alkyl radical, aN = 15.63 +/- 0.06 G and aH = 2.66 +/- 0.03 G, generated as a result of beta-scission of alkoxyl radicals. Spin adduct formation depended on the FeSO4 content of the incubation medium and the number of 22:6-enriched cells present; when the cells were enriched with oleic acid (18:1n-9), spin adducts were not detected. This is the first direct demonstration, using EPR, of a lipid-derived radical formed in intact cells in response to oxidant stress.
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Affiliation(s)
- J A North
- Department of Biochemistry, College of Medicine, University of Iowa, Iowa City 52242
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Abstract
Anthraquinones and anthraquinone derivatives were characterized for their antiviral and virucidal activities against viruses representing several taxonomic groups. One of these compounds, hypericin, had activity against vesicular stomatitis virus, herpes simplex virus types 1 and 2, parainfluenza virus, and vaccinia virus (from 0.5 to 3.8 log10 reductions in infectivity) at concentrations of less than 1 microgram/ml as determined by a direct pre-infection incubation assay. Human rhinovirus was not sensitive to hypericin at concentrations up to 10 micrograms/ml. Addition of small amounts of Tween-80 to solutions containing hypericin enhanced, by up to 2.6 log10, hypericin's virucidal activity. Anthraquinones and anthraquinone derivatives with the hydroxyl and alkyl substitution pattern of emodin (i.e. emodin, emodin anthrone, emodin bianthrone and hypericin) were active against the enveloped viruses tested. The following general pattern of activity was found: hypericin greater than emodin bianthrone greater than emodin anthrone greater than emodin. Chrysophanic acid, aloe-emodin, and sennosides A and B did not possess activity against any of the viruses tested.
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Affiliation(s)
- D O Andersen
- Department of Microbiology, Brigham Young University, Provo, Utah 84602
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Burns CP, Wagner BA, North JA. Effect of hyperthermia on selective expression of HL-60 heat shock proteins. Med Oncol Tumor Pharmacother 1989; 6:245-53. [PMID: 2615528 DOI: 10.1007/bf02985156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hyperthermia is used experimentally to treat human malignancy. The effect of heat delivery rate and thermotolerance on the expression of heat shock proteins (hsp) by the human HL-60 cell line before and after differentiation was studied. This leukemia cell synthesized multiple hsp in response to elevated temperatures. The most obvious and consistent proteins were within the highly conserved stress-inducible family of polypeptides hsp70 which resolved as a hsp69/72 doublet. Cells which were made thermotolerant by gradual heating selectively failed to express the hsp70 doublet even though other hsp were synthesized. Mature HL-60 cells induced to differentiate by incubation in retinoic acid expressed a full complement of hsp when exposed to immediate heat, but there was selective deletion of hsp70 with gradual hyperthermia. This model for selective induction of hsp confirms that synthesis of hsp and thermotolerance can be dissociated in the HL-60. It suggests that the hsp70 does not play an obligatory role in thermotolerance of this human leukemia cell.
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Affiliation(s)
- C P Burns
- Department of Medicine, University of Iowa College of Medicine, Iowa City 52242
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Burns CP, Petersen ES, North JA, Ingraham LM. Effect of docosahexaenoic acid on rate of differentiation of HL-60 human leukemia. Cancer Res 1989; 49:3252-8. [PMID: 2541901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have utilized an experimental model of cell lipid modification that allows study of the effect of a polyunsaturated fatty acid on the linked processes of cellular differentiation and growth arrest. HL-60 human leukemia cells were grown in media supplemented with 10 microM concentrations of the fatty acid docosahexaenoic acid (22:6) or oleic acid (18:1) or in unsupplemented media. Gas chromatographic analysis of phospholipid extracts from HL-60 cells grown in unmodified or 18:1-supplemented media revealed 39% and 36% 18:1, 13 and 12% polyenoics, and 2 and 3% 22:6, respectively. In contrast, cells from 22:6-supplemented cultures had 22% 18:1, 18% total polyunsaturated fatty acids, and 10% 22:6. Retinoic acid was added to cells grown in the various media, and phorbol ester-induced superoxide generation, nitroblue tetrazolium reduction, and growth arrest were determined as measures of differentiation. Unmodified and 18:1-enriched cells showed inducible oxidative burst activity beginning at 48 h after the addition of retinoic acid and continuing to increase for 5 days. In marked contrast, the 22:6-enriched leukemia cells exhibited an increased oxidative activity as early as 24 h which is equivalent to about one division cycle time. G1/0-specific growth arrest was associated with the oxidative phenotypic differentiation in all three cell types. However, cells enriched with 22:6 demonstrated early growth arrest and differentiation considerably in advance of 18:1-modified or unmodified cells. An effect on the cellular differentiation process could be detected after even a brief 1-h exposure of the cells to 22:6. Therefore, a highly polyunsaturated fatty acid which is actively incorporated into membrane structures appreciably accelerates the differentiation process of this human neoplastic cell.
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Affiliation(s)
- C P Burns
- Department of Medicine, University of Iowa College of Medicine, Iowa City 52242
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Burns CP, North JA, Petersen ES, Ingraham LM. Subcellular distribution of doxorubicin: comparison of fatty acid-modified and unmodified cells. Proc Soc Exp Biol Med 1988; 188:455-60. [PMID: 3420109 DOI: 10.3181/00379727-188-42760] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have examined the subcellular localization of doxorubicin and evaluated the effect of fatty acid modification on specific intracellular localization. L1210 leukemia cells enriched with docosahexaenoic acid (22:6) or oleic acid (18:1) were incubated with radiolabeled or unlabeled doxorubicin. After equilibration the cells were ruptured and the subcellular fractions were isolated by differential centrifugation and sucrose gradient separation. The doxorubicin localized primarily in nuclei, as expected, but appreciable amounts were also detected in mitochondria and smaller amounts in plasma membranes, microsomes, and cytoplasm. Subcellular distribution of another anticancer drug which binds to DNA, mitoxantrone, was similar. There were increased amounts of doxorubicin contained in the nuclei and all organelles of the 22:6-enriched cells. Although polyunsaturated fatty acid modification influenced the total amount of doxorubicin in fractions, the relative distribution of drug among the fractions was not different from that of the 18:1-enriched and unmodified cells. We conclude that enrichment with polyunsaturates influences total drug uptake but not proportional distribution of doxorubicin.
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Affiliation(s)
- C P Burns
- Department of Medicine, University of Iowa College of Medicine, Iowa City 52242
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Abstract
We have examined the extent to which it is possible to modify the fatty acid composition of subcellular organelles of L1210 leukemia cells. A polyunsaturated fatty acid, docosahexaenoic acid, or a monounsaturated fatty acid, oleic acid, were added to the culture media. After 48 hr, the cells were ruptured and the subcellular fractions isolated. Fatty acid analysis revealed that nuclei, mitochondria, plasma membranes and microsomes of the cells grown in media supplemented with docosahexaenoic acid contained increased amounts of polyenoic fatty acids compared with cells grown in oleic acid. We conclude that it is possible to experimentally modify the lipids of multiple intracellular structures of L1210 cells by the addition of fatty acids to the growth media.
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Affiliation(s)
- C P Burns
- Department of Medicine, University of Iowa College of Medicine, Iowa City 52242
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Abstract
We have studied the effect of membrane structural alteration on the cellular association of the anticancer drug mitoxantrone whose uptake is not carrier-mediated. Membrane fatty acids of L1210 cells were modified by incubating the cells with the highly unsaturated docosahexaenoic acid (22:6), which results in isolated plasma membranes with 37% of the fatty acids as 22:6, or with the monounsaturated oleic acid (18:1), which results in 58% of the fatty acids as 18:1. The rate of uptake by 22:6-enriched cells during the first min was 62% greater than by those enriched with 18:1. The higher rate was recorded at 0.5-16 microM, pH 6.6-7.6 and temperatures 10-40 C. The difference in cell-associated drug apparently was not due simply to a change in mitoxantrone solubility as measured by partitioning of the drug in lipophilic-hydrophilic systems containing lipids from the fatty-acid altered cells. We conclude that the type of fatty acids contained in L1210 cell membranes can affect the cell association of mitoxantrone. This effect could be on transmembrane flux or be due to differences in binding of the drug to intracellular structures.
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Affiliation(s)
- C P Burns
- Department of Medicine, University of Iowa College of Medicine, Iowa City 52242
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Madsen RD, Weiner LB, McMillan JA, Saeed FA, North JA, Coates SR. Direct detection of Mycoplasma pneumoniae antigen in clinical specimens by a monoclonal antibody immunoblot assay. Am J Clin Pathol 1988; 89:95-9. [PMID: 3122558 DOI: 10.1093/ajcp/89.1.95] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Throat swabs from patients with pharyngitis and sputum specimens from patients with atypical pneumonia were tested for the presence of a Mycoplasma pneumoniae polypeptide with a molecular weight of 43,000 with the use of an M. pneumoniae species-specific monoclonal antibody in an immunoblot assay. This 43,000-dalton polypeptide was detectable in 33 of 33 throat swabs from patients with pharyngitis that were positive for M. pneumoniae by conventional culture as well as a culture-amplified enzyme immunoassay. The 43,000-dalton polypeptide was also detected in three of three M. pneumoniae culture-positive sputum specimens. It was not detected in 3 sputum specimens culture-confirmed for Legionella pneumophila, 10 sputum specimens from normal persons, or 25 throat swabs also from normal persons. This immunoblot assay could be completed within five hours and may be an alternative method for detecting M. pneumoniae antigen directly in sputum or throat swab specimens.
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Affiliation(s)
- R D Madsen
- Cetus Corporation, Emeryville, California 94608
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Abstract
Cisplatin resistance remains poorly understood compared to other forms of anti-neoplastic drug resistance. In this report radiolabeled cisplatin and rapid separation techniques were used to compare drug uptake by L1210 leukemia cells that are sensitive (K25) or resistant (ZCR9) to cisplatin. Uptake of cisplatin by both cell lines was linear without saturation kinetics up to 100 microM. The resistant ZCR9 cells had 36-60% reduced drug uptake as compared to its sensitive parent line, K25. In contrast, there was no difference in the rate of efflux. We conclude that a decreased rate of uptake is one possible mechanism of cellular cisplatin resistance.
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Abstract
Transport of radiolabeled mitoxantrone, a new antineoplastic agent, was studied using cultured mouse L1210 leukemia cells. The initial velocity of influx remained linear for about 90 sec and was 110 pmoles/10(6) cells measured at 60 sec. The steady-state accumulation of about 480 pmoles/10(6) cells was not reached until 30 min. The unidirectional drug influx was linear from 0 to 1000 microM extracellular drug concentration. The initial uptake was relatively temperature independent between 37 degrees and 27 degrees, but accumulation at steady state was 17% lower at 27 degrees. None of six metabolic inhibitors had an appreciable effect on initial uptake. Efflux was initially exponential with a half-life of 2.8 min; this efflux and the residual drug concentration plateau were not affected by KCN or verapamil. Under steady-state conditions, about 86% of the cell-associated label was contained in parent drug and the remainder in an unidentified metabolite. These studies indicate that the mechanism of mitoxantrone uptake is passive diffusion. The efflux is not energy requiring, but there is considerable tight binding of the drug to cellular structures.
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Abstract
The membrane phospholipids of L1210 murine leukemia cells were modified by supplementing the growth medium with micromolar concentrations of polyunsaturated or monounsaturated fatty acids. This procedure results in enrichment of cellular phospholipids by the supplemented fatty acid. Enrichment with polyunsaturated fatty acids resulted in a marked increase in sensitivity to adriamycin as compared to enrichment with monounsaturated fatty acids. The increased cytotoxicity was directly proportional to the extent of unsaturation of the inserted fatty acid, but there was no difference in cells enriched with n-3 compared with n-6 family fatty acids. To explore the mechanism of this observation, we examined whether augmented uptake of the drug might explain the increased cytotoxicity. The uptake of [14C]adriamycin, which was approximately linear at later time points, was only partially temperature dependent and never reached a steady state. Initial uptake at time points prior to 60 s could not be measured due to high and variable rapid membrane adsorption. Cellular accumulation of drug was greater in the docosahexaenoate 22:6-enriched L1210 cells as compared to oleate 18:1-enriched cells and was about 32% greater after 20 min. When L1210 cells were enriched with six fatty acids of variable degrees of unsaturation, the accumulation of adriamycin was directly correlated with the average number of double bonds in the fatty acids contained in cellular phospholipids. There was no difference in efflux of drug from cells pre-loaded with adriamycin. We conclude that the greater accumulation of adriamycin by the polyunsaturated fatty acid-enriched L1210 cells likely explains the increased sensitivity of these cells to adriamycin compared to 18:1-enriched cells.
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Robins RK, Revankar GR, McKernan PA, Murray BK, Kirsi JJ, North JA. The importance of IMP dehydrogenase inhibition in the broad spectrum antiviral activity of ribavirin and selenazofurin. Adv Enzyme Regul 1985; 24:29-43. [PMID: 2872781 DOI: 10.1016/0065-2571(85)90068-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The nucleosides ribavirin, selenazofurin, tiazofurin and bredinin all exhibit the lowering of guanylate pools in vitro and in vivo by the inhibition of IMP dehydrogenase. However, each of these nucleosides has a separate profile of antiviral and antitumor activity. The IMP dehydrogenase inhibition in the case of ribavirin and bredinin appears to be due to the nucleoside 5'-monophosphate and in the case of selenazofurin and tiazofurin to the NAD analogs formed intracellularly. With regard to the antiviral activity of these nucleosides, although selenazofurin was the most potent antiviral agent in vitro, its antiviral activity was also most readily reversed by exogenous guanosine. The antiviral effects of ribavirin were only partially reversed under the conditions studied. These and related studies show that each of these nucleosides form nucleotide metabolites which act as enzyme inhibitors at additional sites other than IMP dehydrogenase. As in the case of ribavirin such inhibition of IMP dehydrogenase may result in an increased "self potentiation" by the lowering of guanylate pools in those instances where guanylate analogs are involved as inhibitors of viral specific or viral induced enzymes. Further studies should more clearly elucidate the importance of the simultaneous inhibition of various enzyme sites by different metabolic nucleotide forms of the same nucleoside analog.
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Kirsi JJ, McKernan PA, Burns NJ, North JA, Murray BK, Robins RK. Broad-spectrum synergistic antiviral activity of selenazofurin and ribavirin. Antimicrob Agents Chemother 1984; 26:466-75. [PMID: 6517540 PMCID: PMC179946 DOI: 10.1128/aac.26.4.466] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The antiviral effects of selenazofurin (2-beta-D-ribofuranosylselenazole-4-carboxamide, selenazole), ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), and 3-deazaguanosine (6-amino-1-beta-D-ribofuranosylimidazo-[4.5-C]pyridin-4(5H)-one) were investigated separately and in various combinations in an in vitro study. The combination interactions were evaluated at seven drug concentrations, graphically (isobolograms) or by using fractional inhibitory concentration indices against mumps, measles, parainfluenza virus type 3, vaccinia and herpes simplex virus type 2 viruses in Vero and HeLa cells. Selenazofurin in combination with ribavirin produced the greatest synergistic antiviral activity. However, the degree of synergy depended on the virus and cell line used. In contrast, selenazofurin combined with 3-deazaguanosine consistently yielded an indifferent or an antagonistic response, or both, whereas the ribavirin-3-deazaguanosine interaction was additive against the same viruses. Single-drug cytotoxicity was minimal for the cytostatic agents selenazofurin and ribavirin but was markedly higher for cytocidal 3-deazaguanosine, as determined by relative plating efficiency after drug exposure. The drug combinations did not significantly increase cytotoxicity (they were only additive) when used on uninfected cells. Therefore, the enhanced antiviral activities of the drug combinations (shown to be synergistic) were due to specific effects against viral replication. These results indicated that in Vero and HeLa cells (i) the combination of selenazofurin and ribavirin produced an enhanced antiviral effect, thus requiring smaller amounts of drug to cause the same antiviral effect relative to a single compound; (ii) selenazofurin when compared with ribavirin and 3-deazaguanosine appeared to have a somewhat different mode of antiviral action; (iii) 3-deazaguanosine combined with selenazofurin was an unsuitable antiviral combination; and (iv) the antiviral activity of 3-deazaguanosine appeared to be due largely to its general overall cytotoxic effect.
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Guffy MM, North JA, Burns CP. Effect of cellular fatty acid alteration on adriamycin sensitivity in cultured L1210 murine leukemia cells. Cancer Res 1984; 44:1863-6. [PMID: 6231987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We have investigated the effect of cellular fatty acid alteration on Adriamycin cytotoxicity using the L1210 lymphoblastic leukemia cell line. Cells growing in Roswell Park Memorial Institute Medium 1640 with 5% fetal bovine serum were modified with respect to fatty acid composition by supplementing their growth medium with 32 microM docosahexaenoic acid (22:6) or oleic acid (18:1). A soft agar clonogenic assay was then used to assess survival following incubation with Adriamycin. When exposed to the drug at a concentration of 0.4 microM, cells grown in the 22:6-supplemented medium were more sensitive (min of drug treatment required to reduce survival by 63% on the exponential portion of the survival curve, 64.9 +/- 4.2 min) to the cytotoxic effects of Adriamycin than cells grown in unsupplemented medium (min of drug treatment required to reduce survival by 63% on the exponential part of the survival curve, 106 +/- 9.7 min) (p less than 0.005). Cytotoxicity of L1210 cells grown in 18:1-supplemented medium was similar to that of cells grown in unsupplemented medium (min of drug treatment required to reduce survival by 63% on the exponential part of the survival curve, 126.6 +/- 9.1 min). The heightened sensitivity to Adriamycin of cells whose medium contained 22:6 increased as the concentration of fatty acid used to supplement the growth medium was increased. The cytotoxicity was also a function of the concentration of Adriamycin from 0.1 to 1.6 microM. When compared to cells grown in unsupplemented medium, those grown in 22:6-supplemented medium contained 3- to 4-fold more polyunsaturated fatty acids in their phospholipids, with a resultant doubling in the mean number of double bonds per fatty acid molecule. These data demonstrate that modification of cellular fatty acid composition may dramatically affect the sensitivity of a tumor cell to Adriamycin.
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Kirsi JJ, North JA, McKernan PA, Murray BK, Canonico PG, Huggins JW, Srivastava PC, Robins RK. Broad-spectrum antiviral activity of 2-beta-D-ribofuranosylselenazole-4-carboxamide, a new antiviral agent. Antimicrob Agents Chemother 1983; 24:353-61. [PMID: 6615611 PMCID: PMC185325 DOI: 10.1128/aac.24.3.353] [Citation(s) in RCA: 133] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The relative in vitro antiviral activities of three related nucleoside carboxamides, ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide), and selenazole (2-beta-D-ribofuranosylselenazole-4-carboxamide), were studied against selected DNA and RNA viruses. Although the activity of selenazole against different viruses varied, it was significantly more potent than ribavirin and tiazofurin against all tested representatives of the families Paramyxoviridae (parainfluenza virus type 3, mumps virus, measles virus), Reoviridae (reovirus type 3), Poxviridae (vaccinia virus), Herpes-viridae (herpes simplex virus types 1 and 2), Togaviridae (Venezuelan equine encephalomyelitis virus, yellow fever virus, Japanese encephalitis virus), Bunyaviridae (Rift Valley fever virus, sandfly fever virus [strain Sicilian], Korean hemorrhagic fever virus), Arenaviridae (Pichinde virus), Picornaviridae (coxsackieviruses B1 and B4, echovirus type 6, encephalomyocarditis virus), Adenoviridae (adenovirus type 2), and Rhabdoviridae (vesicular stomatitis virus). The antiviral activity of selenazole was also cell line dependent, being greatest in HeLa, Vero-76, and Vero E6 cells. Selenazole was relatively nontoxic for Vero, Vero-76, Vero E6, and HeLa cells at concentrations of up to 1,000 micrograms/ml. The relative plating efficiency at that concentration was over 90%. The effects of selenazole on viral replication were greatest when this agent was present at the time of viral infection. The removal of selenazole from the medium of infected cells did not reverse the antiviral effect against vaccinia virus, but there was a gradual resumption of viral replication in cells infected with parainfluenza type 3 or herpes simplex virus type 1 (strain KOS). However, the antiviral activity of ribavirin against the same viruses was reversible when the drug was removed.
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Westover JD, Revankar GR, Robins RK, Madsen RD, Ogden JR, North JA, Mancuso RW, Rousseau RJ, Stephen EL. Synthesis and antiviral activity of certain 9-beta-D-ribofuranosylpurine-6-carboxamides. J Med Chem 1981; 24:941-6. [PMID: 7328597 DOI: 10.1021/jm00140a006] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
To examine the structural parameters necessary for antiviral efficacy of certain purine nucleosides, several 9-beta-D-ribofuranosylpurine-6-carboxamides have been synthesized. Glycosylation of the Me3Si derivative of purine--6-carboxamide with protected ribofuranose in the presence of a Lewis acid gave the blocked nucleoside which on deprotection furnished 9-beta-D-ribofuranosyl-6-iodopurine with cyanide ion. Certain 2-amino- and 2-methyl-9-beta-D-ribofuranosylpurine-6-carboxamides have also been prepared. 8-Carbamoylguanosine (16) has been prepared by homolytic acylation of the parent nucleoside. These compounds were tested against several RNA and DNA viruses in cell culture. 9-beta-D-Ribofuranosylpurine-6-carboxamide (6a), the corresponding 6-thiocarboxamide (7b), and 4-amino-8-(beta-D-ribofuranosylamino)pyrimido[5,4-d]pyrimidine (8) showed significant in vitro antiviral activity at nontoxic dosage levels. 6a employed in the treatment of Rift Valley fever virus infected mice at 50 (mg/kg)/day gave a 55% survival rate on day 21 compared to a 30% survival in the controls.
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Jacobsen SJ, North JA, Rao NA, Mangum JH. 5-methyltetrahydrofolate: synthesis and utilization in normal and SV40-transformed BHK-21 cells. Biochem Biophys Res Commun 1977; 76:46-53. [PMID: 194591 DOI: 10.1016/0006-291x(77)91666-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Kumar PM, North JA, Mangum JH, Rao NA. Cooperative interactions of tetrahydrofolate with purified pig kidney serine transhydroxymethylase and loss of this cooperativity in L1210 tumors and in tissues of mice bearing these tumors. Proc Natl Acad Sci U S A 1976; 73:1950-3. [PMID: 1064865 PMCID: PMC430425 DOI: 10.1073/pnas.73.6.1950] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Serine transhydroxymethylase (5,10-methylenetetrahydrofolate: glycine hydroxymethyl transferase, EC 2.1.2.1) purified 200-fold from pig kidneys showed cooperative interactions with tetrahydrofolate with a Hill coefficient (n value) of 3.9 and a substrate concentration at 50% of maximum velocity, the S(0.5) value, of 0.5 mM. The enzyme in mouse liver and kidney homogenates also showed cooperative interactions with tetrahydrofolate. However, the enzyme obtained from L1210 solid tumors of mice, and from livers and kidneys of mice inoculated with L1210 cells exhibited hyperbolic saturation kinetics and gave a Michaelis constant, Km, value of 0.5 mM for tetrahydrofolate. The interaction of serine with the enzyme from pig kidney, from tissues of normal or tumor-bearing mice, or from L1210 tumors was hyperbolic with a Km of 0.9 mM. The specific activities of the enzyme in the L1210 tumor and in mouse liver were 10-fold higher than in pig or mouse kidney. There was no significant change in the levels of the enzyme in mouse liver and kidney on inoculation with L1210 cells. These results suggest that a tumor can bring about biochemical changes in tissues that are distal to the tumor.
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Draper MW, North JA, Mangum JH. An assay for N 5 -methyltetrahydrofolate-homocysteine transmethylase activity using instant thin-layer chromatography. Anal Biochem 1972; 45:653-7. [PMID: 5060613 DOI: 10.1016/0003-2697(72)90227-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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