Structure and expression of wild-type and suppressible alleles of the Drosophila purple gene.
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.
Kim
N
N
Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea.
Kim
J
J
Park
D
D
Rosen
C
C
Dorsett
D
D
Yim
J
J
D000429:Alcohol Oxidoreductases / Q000235:genetics*; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016386:Chromosome Walking; D017931:DNA Primers; D004330:Drosophila / Q000235:genetics*; D005127:Eye Color / Q000235:genetics; D015870:Gene Expression; D008969:Molecular Sequence Data; D019761:Phosphorus-Oxygen Lyases; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic
D017931:DNA Primers; D000429:Alcohol Oxidoreductases; D019761:Phosphorus-Oxygen Lyases; C043497:6-pyruvoyltetrahydropterin synthase