A new gene in Drosophila melanogaster, Ravus, the phantom of the modifier of position-effect variegation Su(var)3-7.
In a search for homologues of the dominant modifier of position-effect variegation Su(var)3-7, we have identified one ORF in Drosophila melanogaster. The 359 amino acid deduced protein is much shorter than the 1169 amino acid protein Su(var)3-7. Surprisingly, the two genes are very close to each other at 87E on the polytene chromosome map, and are transcribed divergently. The triplet coding for the N-terminus amino acid of the new gene lies only 368 base pairs from the start of transcription of Su(var)3-7. This opposite orientation of the homologue has led us to name it Ravus. The N-terminus of the Ravus protein contains only one of the seven unusual zinc fingers of Su(var)3-7. A second region of similarity encodes an acidic domain. Finally, there is a block of high similarity near the C-terminus of the two proteins. It corresponds to a new conserved protein domain, BESS, found also in the BEAF and Stonewall Drosophila proteins. We have constructed a tagged Ravus protein, and have expressed it as a heat-shock inducible transgene. Ravus associates in vivo with polytene chromosomes but, in contrast to the heterochromatin-associated protein Su(var)3-7, does not show specificity for the chromocenter. Ravus does not seem either to modify the genomic silencing of position-effect variegation, as over-expression of the transgene does not affect the variegated phenotype of a number of rearrangements tested.
Delattre
Marion
M
Department of Zoology and Animal Biology, University of Geneva, Switzerland.
Spierer
Anne
A
Hulo
Nicolas
N
Spierer
Pierre
P
D000595:Amino Acid Sequence; D000818:Animals; D002868:Chromosomal Proteins, Non-Histone / Q000096:biosynthesis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D020224:Expressed Sequence Tags; D006570:Heterochromatin / Q000737:chemistry; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D010641:Phenotype; D017386:Sequence Homology, Amino Acid; D019076:Transgenes
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006570:Heterochromatin; C466085:Ravus protein, Drosophila; C449619:Su(var)3-7 protein, Drosophila