scholarly journals Biosynthesis of the pyrimidine moiety of thiamine. A new route of pyrimidine biosynthesis involving purine intermediates

1968 ◽  
Vol 106 (1) ◽  
pp. 279-287 ◽  
Author(s):  
P. C. Newell ◽  
R G Tucker
Keyword(s):  
Salmonella Typhimurium ◽  
Specific Radioactivity ◽  
Pyrimidine Biosynthesis ◽  
Biosynthetic Pathways ◽  
Purine Pathway ◽  
Growth Requirement ◽  
Pyrimidine Moiety

1. The pattern of distribution on the purine pathway of mutants of Salmonella typhimurium LT2 that had the double growth requirement for a purine plus the pyrimidine moiety of thiamine (ath mutants) indicated that purines and the pyrimidine moiety of thiamine share the early part of their biosynthetic pathways, and that 4-aminoimidazole ribonucleotide (AIR) is the last common intermediate. Two mutants that at first appeared anomalous were further investigated and found not to affect this deduction. 2. The ribonucleoside form of AIR (AIRs) satisfied the requirements both for a purine and for the pyrimidine moiety of thiamine of an ath mutant. 3. Methionine was required for the conversion of AIR into the pyrimidine moiety. 4. Radioactive AIRs was converted into radioactive pyrimidine moiety by an ath mutant without significant dilution of specific radioactivity. 5. Possible mechanisms for pyrimidine-moiety biosynthesis from AIR are discussed.

scholarly journals Precursors of the pyrimidine moiety of thiamine

1968 ◽  
Vol 106 (1) ◽  
pp. 271-277 ◽  
Author(s):  
P. C. Newell ◽  
R G Tucker
Keyword(s):  
Amino Acid ◽  
Salmonella Typhimurium ◽  
Specific Radioactivity ◽  
Cell Suspensions ◽  
Pure Form ◽  
Washed Cell ◽  
Pyrimidine Moiety

1. A method was devised for obtaining the pyrimidine moiety of thiamine in a pure form after its excretion into the medium by de-repressed washed-cell suspensions of mutants of Salmonella typhimurium LT2. 2. By using amino acid-requiring mutants, this excretion of pyrimidine moiety was shown to be dependent on the presence of both methionine and glycine. 3. In the presence of either [Me−14C]methionine or [G−14C]methionine, methionine-requiring mutants did not incorporate radioactivity into the pyrimidine moiety. 4. In contrast, both [1−14C]glycine and [2−14C]glycine were incorporated into the pyrimidine moiety excreted by glycine-requiring mutants, and this occurred with little or no dilution of specific radioactivity. 5. The possible requirement for methionine as a cofactor and the significance of the incorporation of both carbon atoms of glycine are discussed.

scholarly journals Biosynthesis of the Pyrimidine Moiety of Thiamine Independent of the PurF Enzyme (Phosphoribosylpyrophosphate Amidotransferase) in Salmonella typhimurium: Incorporation of Stable Isotope-Labeled Glycine and Formate

1999 ◽  
Vol 181 (3) ◽  
pp. 841-848 ◽  
Author(s):  
Jodi L. Enos-Berlage ◽  
Diana M. Downs
Keyword(s):  
Stable Isotope ◽  
Salmonella Typhimurium ◽  
Isotope Labeling ◽  
De Novo ◽  
Thiamine Pyrophosphate ◽  
Gas Chromatography Mass Spectrometry ◽  
Alternative Route ◽  
Purine Pathway ◽  
Phosphoribosylpyrophosphate Amidotransferase ◽  
Pyrimidine Moiety

ABSTRACT Genetic analyses have suggested that the pyrimidine moiety of thiamine can be synthesized independently of the first enzyme of de novo purine synthesis, phosphoribosylpyrophosphate amidotransferase (PurF), in Salmonella typhimurium. To obtain biochemical evidence for and to further define this proposed synthesis, stable isotope labeling experiments were performed with two compounds, [2-13C]glycine and [13C]formate. These compounds are normally incorporated into thiamine pyrophosphate (TPP) via steps in the purine pathway subsequent to PurF. Gas chromatography-mass spectrometry analyses indicated that both of these compounds were incorporated into the pyrimidine moiety of TPP in apurF mutant. This result clearly demonstrated that the pyrimidine moiety of thiamine was being synthesized in the absence of the PurF enzyme and strongly suggested that this synthesis utilized subsequent enzymes of the purine pathway. These results were consistent with an alternative route to TPP that bypassed only the first enzyme in the purine pathway. Experiments quantitating cellular thiamine monophosphate (TMP) and TPP levels suggested that the alternative route to TPP did not function at the same capacity as the characterized pathway and determined that levels of TMP and TPP in the wild-type strain were significantly altered by the presence of purines in the medium.

scholarly journals THIALYSINE-RESISTANT MUTANT OF SALMONELLA TYPHIMURIUM WITH A LESION IN THE thrA GENE

Genetics ◽  
1976 ◽  
Vol 83 (4) ◽  
pp. 619-632
Author(s):  
Victor A Jegede ◽  
Friederica Spencer ◽  
Jean E Brenchley
Keyword(s):  
Salmonella Typhimurium ◽  
Minimal Medium ◽  
Resistant Mutant ◽  
Enzyme Assays ◽  
Single Mutation ◽  
Homoserine Dehydrogenase ◽  
Genetic Studies ◽  
Inhibition Of Growth ◽  
Growth Requirement ◽  
Pleiotropic Properties

ABSTRACT A mutant of Salmonella typhimurium was selected for its spontaneous resistance to the lysine analog, thialysine (S-2-aminoethyl cysteine). This strain, JB585, exhibits a number of pleiotropic properties including a partial growth requirement for threonine, resistance to thiaisoleucine and azaleucine, excretion of lysine and valine, and inhibition of growth by methionine. Genetic studies show that these properties are caused by a single mutation in the thrA gene which encodes the threonine-controlled aspartokinase-homoserine dehydrogenase activities. Enzyme assays demonstrated that the aspartokinase activity is unstable and the threonine-controlled homoserine dehydrogenase activity absent in extracts prepared from the mutant. These results explain the growth inhibition by methionine because the remaining homoserine dehydrogenase isoenzyme would be repressed by methionine, causing a limitation for threonine. The partial growth requirement for threonine during growth in glucose minimal medium may also, by producing an isoleucine limitation, cause derepression of the isoleucine-valine enzymes and provide an explanation for both the valine excretion, and azaleucine and thiaisoleucine resistance. The overproduction of lysine may confer the thialysine resistance.

Seasonal variation in the composition of the volatile oil of the leaves, buds, and twigs of white spruce (Picea glauca)

1972 ◽  
Vol 50 (7) ◽  
pp. 1595-1603 ◽  
Author(s):  
E. von Rudloff
Keyword(s):  
Seasonal Variation ◽  
Picea Glauca ◽  
Chromatographic Analysis ◽  
Late Summer ◽  
White Spruce ◽  
Volatile Oil ◽  
Quantitative Composition ◽  
Biosynthetic Pathways ◽  
Volatile Terpenes

Gas chromatographic analysis of the volatile terpenes of the leaves, buds, and twigs of white spruce has confirmed that major changes take place only in the new shoots during the early part of summer. Minor changes were recorded for the older shoots during the same period. The relative amounts of β-pinene, limonene, and myrcene in the volatile oil of the buds change significantly during fall and winter. In contrast, the volatile oil of the leaves and twigs remains constant in quantitative composition during late summer, fall, and winter. The sequence in which the relative amounts of each terpene are laid down in the new growth is complex and no correlation with accepted biosynthetic pathways for monoterpenes could be found. During May substantial amounts of sesquiterpenes are present in the new growth, but these appear to be metabolized further as the summer progresses. The implications for chemosystematic studies are discussed.

scholarly journals The apbE Gene Encodes a Lipoprotein Involved in Thiamine Synthesis in Salmonella typhimurium

1998 ◽  
Vol 180 (4) ◽  
pp. 885-891 ◽  
Author(s):  
Brian J. Beck ◽  
Diana M. Downs
Keyword(s):  
Escherichia Coli ◽  
Membrane Protein ◽  
Salmonella Typhimurium ◽  
De Novo ◽  
Open Reading Frame ◽  
Thiamine Pyrophosphate ◽  
Gene Products ◽  
Reading Frame ◽  
Purine Pathway

ABSTRACT Thiamine pyrophosphate is an essential cofactor that is synthesized de novo in Salmonella typhimurium. The biochemical steps and gene products involved in the conversion of aminoimidazole ribotide (AIR), a purine intermediate, to the 4-amino-5-hydroxymethyl-2-methyl pyrimidine (HMP) moiety of thiamine have yet to be elucidated. We have isolated mutations in a new locus (Escherichia coli open reading frame designation yojK) at 49 min on the S. typhimurium chromosome. Two significant phenotypes associated with lesions in this locus (apbE) were identified. First,apbE purF double mutants require thiamine, specifically the HMP moiety. Second, in the presence of adenine, apbE single mutants require thiamine, specifically both the HMP and the thiazole moieties. Together, the phenotypes associated with apbEmutants suggest that flux through the purine pathway has a role in regulating synthesis of the thiazole moiety of thiamine and are consistent with ApbE being involved in the conversion of AIR to HMP. The product of the apbE gene was found to be a 36-kDa membrane-associated lipoprotein, making it the second membrane protein implicated in thiamine synthesis.

Repression of the tyrosine, lysine, and methionine biosynthetic pathways in a hisT mutant of Salmonella typhimurium.

1977 ◽  
Vol 129 (2) ◽  
pp. 1168-1170 ◽  
Author(s):  
B A Brown ◽  
S R Lax ◽  
L Liang ◽  
B J Dabney ◽  
L L Spremulli ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Biosynthetic Pathways
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