Mechanism of suppression in Drosophila. V. Localization of the purple mutant of Drosophila melanogaster in the pteridine biosynthetic pathway

Wilson, Thomas G.; Jacobson, K. Bruce

doi:10.1007/bf00484463

Cited by 25 publications

(9 citation statements)

References 10 publications

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“…Drosophila melanogaster nutants are described in Lindsley and Grell (26), except for Prc4 and prm2b which were isolated recently (Grell and Jacobson, unpublished). Mutants were selected for their abnormal levels of various pteridines: purple (r and bw) are leaky nutants that produce a number of pteridines including drosopterins at -20% of the normal level; sepia (se) produces no drosopterins but does produce elevated levels of several simpler pteridines (sepiapterin, biopterin and pterin); white (w) and brown (bw) are devoid of all pteridines (27,28). Vermilion (v) and cinnabar (cn) are nutants that prevent the synthesis of brown eye pigments; they are used on occasion in combination with the pr mutants so that the red eye pigments (drosopterins) can be observed more directly.…”

Section: Methodsmentioning

confidence: 99%

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Presence of queuine in Drosophila melanogaster: correlation of free pool with queuosine content of tRNA and effect of mutations in pteridine metabolism

1981

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Queuine, a modified form of 7-deazaguanine present in certain transfer RNAs, is shown to occur in Drosophila melanogaster adults in a free form and its concentration varies as a function of age, nutrition and genotype. In several, but not all mutant strains, the concentrations of queuine and the Q(+) (queuine-containing) form of tRNATyr are correlated. The bioassay employs L-M cells which respond to the presence of queuine by an increase in their Q(+)tRNAAsp that is accompanied by a decrease in the Q(-)tRNAAsp isoacceptors. The increase in Q(+)tRNATyr in Drosophila that occurs on a yeast diet is accompanied by an increase in queuine. Similarly the increase of Q(+)tRNAs with age also is accompanied by an increase in free queuine. In two mutants, brown and sepia, these correlations were either diminished or failed to occur. Indeed, the extract of both mutants inhibited the response of the L-M cells to authentic queuine. When the pteridines that occur at abnormally high levels in sepia were used at 1 x 10(-6)M, the inhibition of the L-M cell assay occurred in the order biopterin greater than pterin greater than sepiapterin. These pteridines were also inhibitory for the purified guanine:tRNA transglycosylase from rabbit but the relative effectiveness then was pterin greater than biopterin greater than sepiapterin. Pterin was competitive with guanine in the enzyme reaction with Ki = 0.9 x 10(-7)M. Also when an extract of sepia was chromatographed on Sephadex G-50, the pteridine-containing fractions only were inhibitory toward the L-M cell assay or the enzyme assay. These results indicate that free queuine occurs in Drosophila but also that certain pteridines may interfere with the incorporation of queuine into RNA.

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Section: Methodsmentioning

confidence: 99%

“…respectively, the amounts in wild type (28). In experiment 2, these pteridines were added-to the L-M cells at 1 x 1046M; biopterin and possibly pterin were inhibitory.…”

Section: -mentioning

confidence: 99%

Presence of queuine in Drosophila melanogaster: correlation of free pool with queuosine content of tRNA and effect of mutations in pteridine metabolism

1981

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“…T HE first purple mutation (pr') was isolated more than 75 years ago (BRIDGES 1919). pr' is a leaky spontaneous mutation that results in a purplish-ruby eye color phenotype as a consequence of low pteridine accessory pigment levels (WORN and MITCHELL 1951;WILSON and JACOBSON 1977). The reduced pteridine pigment levels correlate with reduced levels of Gpyruvoyl tetrahydropterin synthase (PTP synthase, originally called sepiapterin synthase A) in the heads of mutant flies (YIM et al 1977;DORSETT et al 1979).…”

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Structure and Expression of Wild-Type and Suppressible Alleles of the Drosophila purple Gene

Kim

Park

et al. 1996

Genetics

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Viable mutant alleles of purple (pr), such as prbw, exhibit mutant eye colors. This reflects low 6-pyruvoyl tetrahydropterin (PTP) synthase activity required for pigment synthesis. PTP synthase is also required for synthesis of the enzyme cofactor biopterin; presumably this is why some pr alleles are lethal. The prbw eye color phenotype is suppressed by suppressor of sable [su(s)] mutations. The pr gene was cloned to explore the mechanism of this suppression. pr produces two PTP synthase mRNAs: one constitutively from a distal promoter and one in late pupae and young adult heads from a proximal promoter. The latter presumably supports eye pigment synthesis. The prbw allele has a 412 retrotransposon in an intron spliced from both mRNAs. However, the head-specific mRNA is reduced >10-fold in prbw and is restored by a su(s) mutation, while the constitutive transcript is barely affected. The Su(s) protein probably alters processing of RNA containing 412. Because the intron containing 412 is the first in the head-specific mRNA and the second in the constitutive mRNA, binding of splicing machinery to nascent transcripts before the 412 insertion is transcribed may preclude the effects of Su(s) protein.

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“…Quench spot (QS) is an unidentified compound that has been found and quantitated in wild-type, pr, sepia (se), and Henna-recessive-3 (Hrí3) flies (Wilson & Jacobson, 1977b). Purple, which contains low levels of sepiapterin and drosopterins, also has low levels of QS.…”

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Purification and biosynthesis of quench spot, a drosopterin precursor in Drosophila melanogaster

Dorsett¹,

Kb²

1982

Biochemistry

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Pteridine biosynthesis has been examined in extracts of the heads of Drosophila melanogaster by measuring the conversion of dihydroneopterin triphosphate to sepiapterin and the "drosopterins" (six eye pigments that are dipterin derivatives). These two products share a common first step in the production of an intermediate that is a branch point from which both products are formed. This first step can be catalyzed by sepiapterin synthase or by an enzyme found in particles that sediment at 600g. A substance named "quench spot" was found earlier to be at low levels in the purple mutants that were defective in drosopterin synthesis and to be restored to normal when a suppressor mutant, su(s)2, restored drosopterins in purple to normal levels. The sepia mutant is also deficient in the levels of both quench spot and drosopterins. In this report we propose that quench spot is a precursor of drosopterins, but not sepiapterin, and that it is formed from the sepiapterin synthase intermediate mentioned above. An additional precursor that is formed independently of the sepiapterin synthase pathway is also proposed that would react with quench spot to form drosopterins. These proposals are based on the following: (1) quench spot biosynthesis is observed in extracts of Drosophila heads in which [U-14C]dihydroneopterin triphosphate is the substrate; (2) Mg2+ is required for the synthesis of quench spot but either NADH or NADPH causes diminished incorporation of the label; (3) extracts from heads of a purple mutant (prbwcn) contain only 30% of the quench spot biosynthetic activity as compared to heads from wild type (Oregon-R); (4) quench spot has been purified from heads of wild-type Drosophila; (5) addition of quench spot stimulates the biosynthesis of drosopterins in an enzyme preparation from Oregon-R.

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Mechanism of suppression in Drosophila. V. Localization of the purple mutant of Drosophila melanogaster in the pteridine biosynthetic pathway

Cited by 25 publications

References 10 publications

Presence of queuine in Drosophila melanogaster: correlation of free pool with queuosine content of tRNA and effect of mutations in pteridine metabolism

Presence of queuine in Drosophila melanogaster: correlation of free pool with queuosine content of tRNA and effect of mutations in pteridine metabolism

Structure and Expression of Wild-Type and Suppressible Alleles of the Drosophila purple Gene

Purification and biosynthesis of quench spot, a drosopterin precursor in Drosophila melanogaster

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