The Drosophila gene taranis encodes a novel trithorax group member potentially linked to the cell cycle regulatory apparatus.
Genes of the Drosophila Polycomb and trithorax groups (PcG and trxG, respectively) influence gene expression by modulating chromatin structure. Segmental expression of homeotic loci (HOM) initiated in early embryogenesis is maintained by a balance of antagonistic PcG (repressor) and trxG (activator) activities. Here we identify a novel trxG family member, taranis (tara), on the basis of the following criteria: (i) tara loss-of-function mutations act as genetic antagonists of the PcG genes Polycomb and polyhomeotic and (ii) they enhance the phenotypic effects of mutations in the trxG genes trithorax (trx), brahma (brm), and osa. In addition, reduced tara activity can mimic homeotic loss-of-function phenotypes, as is often the case for trxG genes. tara encodes two closely related 96-kD protein isoforms (TARA-alpha/-beta) derived from broadly expressed alternative promoters. Genetic and phenotypic rescue experiments indicate that the TARA-alpha/-beta proteins are functionally redundant. The TARA proteins share evolutionarily conserved motifs with several recently characterized mammalian nuclear proteins, including the cyclin-dependent kinase regulator TRIP-Br1/p34(SEI-1), the related protein TRIP-Br2/Y127, and RBT1, a partner of replication protein A. These data raise the possibility that TARA-alpha/-beta play a role in integrating chromatin structure with cell cycle regulation.
Calgaro
Stéphane
S
Centre de Biologie du Développement, Université Paul Sabatier, 31062 Toulouse Cedex, France.
Boube
Muriel
M
Cribbs
David L
DL
Bourbon
Henri-Marc
HM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle / Q000235:genetics* / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics* / Q000502:physiology; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology
D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C096658:pb protein, Drosophila; C454818:tara protein, Drosophila