N-terminus of Drosophila MSL1 interacts with DNA-binding proteins and is critical for the recruitment of the dosage compensation complex to the X chromosome

Abstract

ABSTRACTThe male-specific lethal dosage compensation complex (MSL complex or DCC), which consists of five proteins and two non-coding roX RNAs, is necessary for the transcriptional enhancement of X-linked genes to compensate for the sex chromosome monosomy inDrosophilaXY males, compared with XX females. MSL2 is a single protein component of the DCC that is expressed only in males and is essential for the specific recruitment of the DCC to the high-affinity “entry” sites (HASs) on the X chromosome. MSL2, together with MSL1, forms the heterotetrameric DCC core. Here, we demonstrated that the N-terminal unstructured region of MSL1 interacts with many different DNA-binding proteins that contain clusters of the C2H2 zinc-finger domains. Amino acid deletions in the N-terminal region of MSL1 strongly affect the binding of the DCC to the HASs on the male X chromosome. However, the binding of MSL2 to autosomal promoters was unaffected by amino acid deletions in MSL1. Males expressing mutant variants of MSL1 died during the larvae stage, demonstrating the critical role played by the N-terminal region in DCC activity. Our results suggest that MSL1 interacts with a variety of DNA-binding proteins to increase the specificity of DCC recruitment to the male X chromosome.BulletsThe N-terminal region of MSL1 interacts with 14 C2H2-type zinc-finger DNA-binding proteinsThe N-terminus of MSL1 is critical for the specific recruitment of the MSL complex to the X chromosomeThe N-terminus of MSL1 is important for the binding of MSL2 to a small fraction of autosomal promoters