DNA Repair and Transcriptional Deficiencies Caused by Mutations in the Drosophila p52 Subunit of TFIIH Generate Developmental Defects and Chromosome Fragility

Abstract

The transcription and DNA repair factor TFIIH is composed of 10 subunits. Mutations in the XPB, XPD, and p8 subunits are genetically linked to human diseases, including cancer. However, no reports of mutations in other TFIIH subunits have been reported in higher eukaryotes. Here, we analyze at genetic, molecular, and biochemical levels the Drosophila melanogaster p52 (DMP52) subunit of TFIIH. We found that DMP52 is encoded by the gene marionette in Drosophila and that a defective DMP52 produces UV light-sensitive flies and specific phenotypes during development: organisms are smaller than their wild-type siblings and present tumors and chromosomal instability. The human homologue of DMP52 partially rescues some of these phenotypes. Some of the defects observed in the fly caused by mutations in DMP52 generate trichothiodystrophy and cancer-like phenotypes. Biochemical analysis of DMP52 point mutations introduced in human p52 at positions homologous to those of defects in DMP52 destabilize the interaction between p52 and XPB, another TFIIH subunit, thus compromising the assembly of the complex. This study significantly extends the role of p52 in regulating XPB ATPase activity and, consequently, both its transcriptional and nucleotide excision repair functions.

We thank V. Walbot for criticism and discussion of the manuscript, V. Barajas for technical advice, and Andres Saralegui for help with the confocal images. We also thank C. Brawn for technical advice. We are grateful to I. Kolb-Cheynel and J. L. Weickert for the production of recombinant baculoviruses.

This study was supported by funds from l'Association de la Recherche contre le Cancer (no. 3113), from l'Institut des Maladies Rares (A03098MS), and from the European Community (no. LSHC-CT-2005-512113.) to J.-M.E. and from PAPIIT/UNAM, CONACyT, and the Howard Hughes Medical Institute to M.Z.