Targeting the chromatin-remodeling MSL complex of Drosophila to its sites of action on the X chromosome requires both acetyl transferase and ATPase activities

Dosage compensation in Drosophila is mediated by a multiprotein, RNA-contai ning complex that associates with the X chromosome at multiple sites. We ha ve investigated the role that the enzymatic activities of two complex compo nents, the histone acetyltransferase activity of MOF and the ATPase activit y of MLE, may have in the targeting and association of the complex with the X chromosome. Here we report that MLE and MOF activities are necessary for complexes to access the various X chromosome sites. The role that histone H4 acetylation plays in this process is supported by our observations that MOF overexpression leads to the ectopic association of the complex with aut osomal sites.