Purine synthesis de novo and salvage in hypoxanthine phosphoribosyltransferase-deficient mice

1989 ◽  
Vol 17 (3) ◽  
pp. 578-579 ◽  
Author(s):  
JENNIFER ALLSOP ◽  
RICHARD W. E. WATTS
Keyword(s):  
De Novo ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Purine Synthesis ◽  
Deficient Mice

Guanosine metabolism in Neurospora crassa

1980 ◽  
Vol 58 (5) ◽  
pp. 369-376 ◽  
Author(s):  
W. L. Greer ◽  
L. Pendyala ◽  
A. M. Wellman
Keyword(s):  
Neurospora Crassa ◽  
Biosynthetic Pathway ◽  
De Novo ◽  
Nutritional Supplement ◽  
Inhibitory Effect ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Wild Type ◽  
Adenine Phosphoribosyltransferase ◽  
Purine Synthesis ◽  
De Novo Biosynthesis

Two aspects of guanosine metabolism in Neurospora have been investigated, (a) The inability of adenine mutants (blocked prior to IMP synthesis) to use guanosine as a nutritional supplement; and (b) the inhibitory effect of guanosine on the utilization of hypoxanthine as a purine source for growth by these mutants. Studies on the utilization of guanosine indicated that the proportion of adenine derived from guanosine may be limiting for the growth of adenine mutants. In wild type, adenine is produced through the biosynthetic pathway when grown in the presence of guanosine The amount of adenine produced through the de novo biosynthesis in wild type increases with increasing concentrations of guanosine in the medium. However, the total purine synthesis does not increase. Guanosine inhibits the uptake of hypoxanthine severely. In addition, guanosine and its nucleotide derivatives also inhibit the hypoxanthine phosphoribosyltransferase activity, at the same time stimulating the adenine phosphoribosyltransferase activity. Guanosine's effects on the uptake of hypoxanthine and its conversion to the nucleotide form may be the reasons why guanosine inhibits the utilization of hypoxanthine but not adenine by these mutants.

scholarly journals A new folate antimetabolite, 5,10-dideaza-5,6,7,8-tetrahydrofolate is a potent inhibitor of de novo purine synthesis

1989 ◽  
Vol 264 (1) ◽  
pp. 328-333 ◽  
Author(s):  
G P Beardsley ◽  
B A Moroson ◽  
E C Taylor ◽  
R G Moran
Keyword(s):  
De Novo ◽  
Potent Inhibitor ◽  
Purine Synthesis

scholarly journals Monocyte Subsets with High Osteoclastogenic Potential and Their Epigenetic Regulation Orchestrated by IRF8

2020 ◽  
Author(s):  
Amitabh Das ◽  
Xiaobei Wang ◽  
Jessica Kang ◽  
Alyssa Coulter ◽  
Amol C. Shetty ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Nuclear Translocation ◽  
De Novo ◽  
Primary Source ◽  
Regulatory Elements ◽  
Monocyte Subsets ◽  
Enhancer Activity ◽  
Signaling Receptors ◽  
Early Developmental ◽  
Deficient Mice

SUMMARYOsteoclasts (OCs) are bone resorbing cells formed by the serial fusion of monocytes. In mice and humans, three distinct subsets of monocytes exist; however, it is unclear if all of them exhibit osteoclastogenic potential. Here we show that in wild-type mice, Ly6Chi and Ly6Cint monocytes are the primary source of OC formation when compared to Ly6C− monocytes. Their osteoclastogenic potential is dictated by increased expression of signaling receptors and activation of pre-established transcripts, as well as de novo gain in enhancer activity and promoter changes. In the absence of IRF8, a transcription factor important for myelopoiesis and osteoclastogenesis, all three monocyte subsets are programmed to display higher osteoclastogenic potential. Enhanced NFATc1 nuclear translocation and amplified transcriptomic and epigenetic changes initiated at early developmental stages direct the increased osteoclastogenesis in Irf8 deficient mice. Collectively, our study provides novel insights into the transcription factors and active cis-regulatory elements that regulate OC differentiation.

Molecular genetic analysis of Saccharomyces cerevisiae C1-tetrahydrofolate synthase mutants reveals a noncatalytic function of the ADE3 gene product and an additional folate-dependent enzyme

1990 ◽  
Vol 10 (11) ◽  
pp. 5679-5687
Author(s):  
C K Barlowe ◽  
D R Appling
Keyword(s):  
Saccharomyces Cerevisiae ◽  
De Novo ◽  
Point Mutations ◽  
Gene Replacement ◽  
Molecular Genetic Analysis ◽  
Yeast Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Purine Synthesis

In eucaryotes, 10-formyltetrahydrofolate (formyl-THF) synthetase, 5,10-methenyl-THF cyclohydrolase, and NADP(+)-dependent 5,10-methylene-THF dehydrogenase activities are present on a single polypeptide termed C1-THF synthase. This trifunctional enzyme, encoded by the ADE3 gene in the yeast Saccharomyces cerevisiae, is thought to be responsible for the synthesis of the one-carbon donor 10-formyl-THF for de novo purine synthesis. Deletion of the ADE3 gene causes adenine auxotrophy, presumably as a result of the lack of cytoplasmic 10-formyl-THF. In this report, defined point mutations that affected one or more of the catalytic activities of yeast C1-THF synthase were generated in vitro and transferred to the chromosomal ADE3 locus by gene replacement. In contrast to ADE3 deletions, point mutations that inactivated all three activities of C1-THF synthase did not result in an adenine requirement. Heterologous expression of the Clostridium acidiurici gene encoding a monofunctional 10-formyl-THF synthetase in an ade3 deletion strain did not restore growth in the absence of adenine, even though the monofunctional synthetase was catalytically competent in vivo. These results indicate that adequate cytoplasmic 10-formyl-THF can be produced by an enzyme(s) other than C1-THF synthase, but efficient utilization of that 10-formyl-THF for purine synthesis requires a nonenzymatic function of C1-THF synthase. A monofunctional 5,10-methylene-THF dehydrogenase, dependent on NAD+ for catalysis, has been identified and purified from yeast cells (C. K. Barlowe and D. R. Appling, Biochemistry 29:7089-7094, 1990). We propose that the characteristics of strains expressing full-length but catalytically inactive C1-THF synthase could result from the formation of a purine-synthesizing multienzyme complex involving the structurally unchanged C1-THF synthase and that production of the necessary one-carbon units in these strains is accomplished by an NAD+ -dependent 5,10-methylene-THF dehydrogenase.

scholarly journals The Last Enzyme of the De Novo Purine Synthesis Pathway 5-aminoimidazole-4-carboxamide Ribonucleotide Formyltransferase/IMP Cyclohydrolase (ATIC) Plays a Central Role in Insulin Signaling and the Golgi/Endosomes Protein Network

2015 ◽  
Vol 14 (4) ◽  
pp. 1079-1092 ◽  
Author(s):  
Martial Boutchueng-Djidjou ◽  
Gabriel Collard-Simard ◽  
Suzanne Fortier ◽  
Sébastien S. Hébert ◽  
Isabelle Kelly ◽  
...  
Keyword(s):  
Insulin Signaling ◽  
De Novo ◽  
Protein Network ◽  
Purine Synthesis
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