DROSOPHILA NURF-55, A WD REPEAT PROTEIN INVOLVED IN HISTONE METABOLISM

The Drosophila nucleosome remodeling factor (NURF) is a protein comple x of four distinct subunits that assists transcription factor-mediated chromatin remodeling. One NURF subunit, ISWI, is related to the trans criptional regulators Drosophila brahma and yeast SW12/SNF2. We have d etermined peptide sequences and isolated cDNA clones for a second NURF component (the 55-kDa subunit). Immunological studies show that p55 i s an integral subunit of NURF and is generally associated with polyten e chromosomes. The predicted sequence of p55 reveals a WD repeat prote in that is identical with the 55-kDa subunit of the Drosophila chromat in assembly factor (CAF-1). Given that WD repeat proteins related to p 55 are associated with histone deacetylase and histone acetyltransfera se, our findings suggest that p55 and its homologs may function as a c ommon platform for the assembly of protein complexes involved in chrom atin metabolism.