Superfamily I helicases as modular components of DNA-processing machines

2011 ◽  
Vol 39 (2) ◽  
pp. 413-423 ◽  
Author(s):  
Mark S. Dillingham
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Molecular Mechanisms ◽  
Acid Metabolism ◽  
Nucleic Acid Metabolism ◽  
Cellular Functions ◽  
Dna Helicases ◽  
Wide Range ◽  
Look Back ◽  
Partner Proteins

Helicases are a ubiquitous and abundant group of motor proteins that couple NTP binding and hydrolysis to processive unwinding of nucleic acids. By targeting this activity to a wide range of specific substrates, and by coupling it with other catalytic functionality, helicases fulfil diverse roles in virtually all aspects of nucleic acid metabolism. The present review takes a look back at our efforts to elucidate the molecular mechanisms of UvrD-like DNA helicases. Using these well-studied enzymes as examples, we also discuss how helicases are programmed by interactions with partner proteins to participate in specific cellular functions.

scholarly journals Helicase Mechanisms During Homologous Recombination inSaccharomyces cerevisiae

2019 ◽  
Vol 48 (1) ◽  
pp. 255-273 ◽  
Author(s):  
J. Brooks Crickard ◽  
Eric C. Greene
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nucleic Acid ◽  
Homologous Recombination ◽  
Nucleic Acids ◽  
Acid Metabolism ◽  
Model Organism ◽  
Nucleic Acid Metabolism ◽  
Repair Pathway ◽  
Unidirectional Movement ◽  
Nucleoprotein Complexes

Helicases are enzymes that move, manage, and manipulate nucleic acids. They can be subdivided into six super families and are required for all aspects of nucleic acid metabolism. In general, all helicases function by converting the chemical energy stored in the bond between the gamma and beta phosphates of adenosine triphosphate into mechanical work, which results in the unidirectional movement of the helicase protein along one strand of a nucleic acid. The results of this translocation activity can range from separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. In this review, we focus on describing key helicases from the model organism Saccharomyces cerevisiae that contribute to the regulation of homologous recombination, which is an essential DNA repair pathway for fixing damaged chromosomes.

scholarly journals Nucleic acid metabolism in the ruminant

1969 ◽  
Vol 23 (3) ◽  
pp. 671-682 ◽  
Author(s):  
A. B. Mcallan ◽  
R. H. Smith
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Acid Solution ◽  
Perchloric Acid ◽  
Trichloroacetic Acid ◽  
Acid Metabolism ◽  
Nucleic Acid Metabolism ◽  
Trichloroacetic Acid Solution ◽  
Rna And Dna

1. Procedures, based on those of Schmidt & Thannhauser (1945) and Schneider (1945), for the extraction and estimation of nucleic acids in bovine digesta were examined in detail.2. Final methods which were suitable for routine determination of RNA and DNA were essentially as follows. Digesta samples were extracted in the cold, first with a solution of trichloroacetic acid in ethanol, then with aqueous trichloroacetic acid solution and finally with lipid solvents. The dried residue was hydrolysed with alkali, purified by passage through a Dowex resin, and the RNA, in the form of mononucleotides, determined by U.V. absorption. DNA was determined separately in hot perchloric acid extracts of the original dried residue by colorimetric estimation of the deoxyribose content.

Therapeutic Nucleic Acids: A Potential Source of Resistance to Cancer, Antiviral and Immunosuppressive Therapy.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1614-1614 ◽  
Author(s):  
Raymund Buhmann ◽  
Ting Yang ◽  
Monica Schifferer ◽  
Martin Obermeier ◽  
Gundula Jaeger ◽  
...  
Keyword(s):  
Mycophenolate Mofetil ◽  
Nucleic Acid ◽  
Nucleic Acids ◽  
Antiviral Therapy ◽  
Immunosuppressive Therapy ◽  
Acid Metabolism ◽  
Nucleic Acid Metabolism ◽  
Inosine Monophosphate Dehydrogenase ◽  
Nucleotide Synthesis ◽  
Standard Drug

Abstract According to their unique structural and chemical properties nucleic acids were recognized to provide inherent therapeutic potential beyond sole information storage. In the meantime an increasing number of nucleic acid based drugs achieved FDA approval and entered clinical trails (e.g. “antisense” or “immunosustimulatory CpG” oligodeoxynucletides (ODNs), aptamers, ribozymes, RNA interference or defibrotide). But so far, no or less information is available whether these compounds might compete with chemically and structurally related drugs, e.g. nucleoside analogues (NA) widely used in cancer or antiviral therapy, or interfere with the intracellular nucleic acid metabolism. In the present report we provide evidence, that nucleic-acid based drugs antagonize fludarabine, acyclovir or mycophenolate mofetil (MMF). In presence of defibrotide (DF), a polydisperse mixture of single-stranded oligodeoxyribonucleotides (15 to 30 kD) e.g. used for treatment of hepatic veno-occlusive disease and other endothelial disorders, fludarabine treated lymphocytes or myeloid blasts where rescued from apoptosis. According to nucleic acid degradation the resulting metabolite deoxycytidine turned out to be the key substrate competing with fludarabine for phosphorylation by deoxycitidine kinase (dCK) and suggested interference with nucleic acid metabolism rather than direct competition with the drug for cellular uptake. Moreover, in standard drug resistance assays using acyclovir sensitive herpes simplex virus (HSV) strains (V0631508), 4 mM of DF restored viral replication in presence of 50 mM acyclovir. This was confirmed by quantitative PCR of viral DNA. Here, deoxythymidine turned out to be the main competitor for intracellular phosphorylation mediated by virus thymidine kinase. To further extent our findings, that an increase of the extracellular concentration of nucleic acids directly interfere with the intracellular nucleic acid metabolism, mixed lymphocyte reactions (MLRs) were performed, to test whether the immunosuppressive effects of mycophenolate mofetil (MMF) could be reversed. As control cyclosporine A (CsA) was used. Here, addition of singular ribonucleotides almost completely antagonized the T cell inhibitory effects of mycophenolic acid (MPA), respectively its prodrug MMF, but not of CsA. As MPA is known to be a potent, selective, uncompetitive and reversible inhibitor of inosine monophosphate dehydrogenase, a key enzyme for the de novo pathway of guanosine nucleotide synthesis, addition of guanosine to the MLRs was found to be effective and sufficient to reverse the immunosuppressive effects of MPA. We conclude that treatment with nucleic-acid-based drugs interfere with the intracellular nucleic acid metabolism, thus decreasing the efficacy of NAs used for cancer and antiviral therapy or the immunosuppressive therapy using MMF. Prospective clinical trials are required to confirm these in vitro findings.

Picloram Sensitivity and Nucleic Acids in Plants

Weed Science ◽  
1970 ◽  
Vol 18 (1) ◽  
pp. 1-4 ◽  
Author(s):  
S. S. Malhotra ◽  
J. B. Hanson
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Herbicide Resistance ◽  
Dna Content ◽  
Acid Metabolism ◽  
Nucleic Acid Metabolism ◽  
Sensitive Species ◽  
Total Rna ◽  
Resistant Species ◽  
Rna And Dna

The changes in the nucleic acid metabolism were studied in plants susceptible and resistant to 4-amino-3,5,6-trichloropicolinic acid (picloram). The total RNA and DNA content of the tissue correlated inversely with the herbicide resistance; the resistant plants were low in nucleic acids, whereas sensitive plants were high. The increase in the nucleic acids of the sensitive species 24 hr after picloram treatment appeared to be associated with lower levels of ribonuclease and deoxyribonuclease. The inability of the resistant species to make more RNA may be associated with high levels of nucleases in the tissue.

scholarly journals Nucleic acids in the last stages of maturation of two varieties

2015 ◽  
Vol 46 (4) ◽  
pp. 691-700
Author(s):  
R. Górecki ◽  
S. Grzesiuk ◽  
A. Rejowski
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Column Chromatography ◽  
Acid Metabolism ◽  
Nucleic Acid Metabolism ◽  
Wheat Grain ◽  
5S Rna ◽  
Chromatography Method ◽  
Wheat Embryos

Using the MAK column chromatography method the process of wheat grain maturation was found to be closely correlated with nucleic acid metabolism. The amount of nucleic acids in the embryos increased until the end of the maturation of the grain. This increase was the result of an intensive synthesis mainly of rRNA fractions and to some extent also of sRNA. The quantitative proportion of various fractions of nucleic acids also changed in the last stages of grain maturation. In the period of wax maturity in wheat embryos a higher content of 4S and 5S RNA was found which partly explains a higher viability of these seeds.

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