Genetic fine structure and function of mutants at the ilv1-gene locus of Saccharomyces cerevisiae

Thuriaux, Pierre; Minét, Michèle; Berge, A. M. A. ten; Zimmermann, Friedrich K.

doi:10.1007/bf00266933

Cited by 24 publications

(9 citation statements)

References 23 publications

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“…As can be seen in Table 1, D106-1A gives neither partial derepression of synthetase when grown on minimal medium containing the growth requirements, nor complete derepression when grown on limiting isoleucine. The lack of derepression by D106-1A under these conditions contrasts with the derepression of synthetase obtained when M21 is grown under the (29) and MI21 a missense mutation (18) in ilvi. APB 1 to 6 are six ilv1 + revertants of D106-1A, and APB 7 contains a suppressor for the D106-1A nonsense mutation.…”

Section: Methods and Resultsmentioning

confidence: 63%

“…A nonsense mutation in the threonine deatninase gene affects the levels of acetohydroxy acid synthetase Strain D106-1A, which has a nonsense mutation in the middle of ilvI, the gene for threonine deaminase (29), and is in addition a leucine auxotroph, was grown in the following media: (a) repressing medium, (b) minimal medium containing nonrepressing concentrations of L-leucine and L-isoleucine, and (c) medium containing a nonrepressing concentration of leucine and a limiting supply of isoleucine, which was fur-2169 nished either by supplementing the culture with 1.5 mM isoleucylglycine or by inhibition by valine of isoleucine uptake (11). M21, a missense mutant of ilv1, was grown under the same conditions.…”

Section: Methods and Resultsmentioning

confidence: 99%

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Involvement of Threonine Deaminase in Multivalent Repression of the Isoleucine-Valine Pathway in Saccharomyces cerevisiae

Bollon

Magee

1971

Proc. Natl. Acad. Sci. U.S.A.

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A strain (MIAR33) of Saccharomyces cerevisiae containing a threonine deaminase [L-threonine hydrolyase (deaminating) EC 4.2.1.161 with decreased feedback sensitivity has been shown to have a specific activity of acetohydroxy acid synthetase higher than that of the parent strain (MDIll) when both are grown on minimal medium. When strain MAR33 is grown on minimal medium supplemented only with isoleucine, the specific activity of the synthetase is reduced to that found in the parent strain. Another strain, D106-lA, contains a nonsense mutation in the middle of the gene for threonine deaminase. When this strain is grown on minimal medium containing appropriate supplements (which include a nonrepressing concentration of isoleucine), or on minimal medium supplemented with isoleucylglycine (which acts as a limiting source of isoleucine), acetohydroxy acid synthetase remains repressed. Leucine limitation causes partial derepression. With the reversion of the nonsense mutation, either intragenically or via a suppressor for the mutation, partial derepression of the synthetase returns. When D106-lA is diploidized with either M15, a mutant lacking the synthetase, or MD9, a strain containing the enzyme, normal, partially derepressed, values for this enzyme are found. This indicates that threonine deaminase is necessary for derepression, and that it possibly acts as an inducer.The involvement of a biosynthetic enzyme of a specific aminoacid pathway in repression of other enzymes of the same pathway has been considered by several investigators (1-7).Our possession of several mutants affected in the allosteric properties of threonine deaminase permitted us to explore the involvement of this enzyme in the repression of acetohydroxy acid synthetase in Saccharomyces cerevisiae. Threonine deaminase and acetohydroxy acid synthetase are the first two enzymes in the isoleucine-valine biosynthetic pathway. The properties of these two enzymes in S. cerevisiae have been examined (8-10). Regulation of the isoleucinevaline pathway has been examined in S. cerevisiae (11, 12), in Escherichia coli (13-15), and in Salmonella typhimurium (16). All of these organisms show multivalent repression of at least some of the enzymes of the pathway. Full repression occurs only in the presence of all three aminio acids: isoleucine, valine, and leucine. Starvation for one of these compounds causes derepression of the enzymes of the pathway, even in the presence of an excess of the other two ( 1). METHODS AND RESULTSThtreonine deaminase mutated in its allosteric properties and the repression of acetohydroxy acid synthetase MAR33, a haploid strain of S. cerevisiae, contains a single mutation that renders threonine deaminiase 100-fold less sensitive to isoleucine inhibition than the enzyme of MD11 (the parent strain) (17). Parent and mutant strains were grown inl minimal and repressing medium, which is minimal medium supplemented with isoleucine, valine, and leucine, each at 5 mM\. The cultures were made permeable with toluene, and the acetohydroxy a...

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Section: Methods and Resultsmentioning

confidence: 63%

Section: Methods and Resultsmentioning

confidence: 99%

Involvement of Threonine Deaminase in Multivalent Repression of the Isoleucine-Valine Pathway in Saccharomyces cerevisiae

Bollon

Magee

1971

Proc. Natl. Acad. Sci. U.S.A.

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“…The genetic fine structure analysis of 27 point mutations at the ilvl locus by THURIAUX et al (44) showed that it consists of only one cistron. Interallelic complementation at ilvl suggested that the product was composed of at least two identical polypeptide chains.…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning and characterization of the threonine deaminase (ILV1) gene of Saccharomyces cerevisiae

Petersen

Holmberg

Nilsson-Tillgren

et al. 1983

Carlsberg Res. Commun.

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“…Dithizone was used in preference to a Timm stain because of its relative simplicity and because it is a somewhat more specific indicator for zinc. 18. These results should be viewed with caution, since two of the rats died after receiving about SCIENCE, VOL.…”

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confidence: 92%

Genetic Effects of Impure and Pure Saccharin in Yeast

Moore

Schmick

1979

Science

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Yeast cells were grown in media containing impure or purified saccharin preparations. Dose-dependent increases in frequencies of cells possessing aberrant cell morphologies were revealed by light microscopy. At each test dose, cells grown in impure saccharin exhibited up to sevenfold higher frequencies of mitotic crossing-over or gene conversion in three of four assays for genetic recombination than cells grown in purified saccharin from the same lot. With one exception, the sweetener produced by the Maumee process caused larger increases in recombination and gene reversion than the sweetener produced by the Remsen-Fahlberg process. The several test markers did not respond equally to any test saccharin. Cells grown in liquid media containing no saccharin or two of three test concentrations of saccharin produced cell titers that were approximately equivalent.

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Genetic fine structure and function of mutants at the ilv1-gene locus of Saccharomyces cerevisiae

Cited by 24 publications

References 23 publications

Involvement of Threonine Deaminase in Multivalent Repression of the Isoleucine-Valine Pathway in Saccharomyces cerevisiae

Involvement of Threonine Deaminase in Multivalent Repression of the Isoleucine-Valine Pathway in Saccharomyces cerevisiae

Molecular cloning and characterization of the threonine deaminase (ILV1) gene of Saccharomyces cerevisiae

Genetic Effects of Impure and Pure Saccharin in Yeast

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