4b7y
Crystal structure of the MSL1-MSL2 complex
Structural highlights
FunctionMSL2_HUMAN Component of histone acetyltransferase complex responsible for the majority of histone H4 acetylation at lysine 16 which is implicated in the formation of higher-order chromatin structure. Acts as an E3 ubiquitin ligase that promotes monoubiquitination of histone H2B at 'Lys-35' (H2BK34Ub), but not that of H2A. This activity is greatly enhanced by heterodimerization with MSL1. H2B ubiquitination in turn stimulates histine H3 methylation at 'Lys-4' (H3K4me) and 'Lys-79' (H3K79me) and leads to gene activation, including that of HOXA9 and MEIS1.[1] Publication Abstract from PubMedThe Male-Specific Lethal (MSL) complex regulates dosage compensation of the male X chromosome in Drosophila. Here, we report the crystal structure of its MSL1/MSL2 core, where two MSL2 subunits bind to a dimer formed by two molecules of MSL1. Analysis of structure-based mutants revealed that MSL2 can only interact with the MSL1 dimer, but MSL1 dimerization is MSL2 independent. We show that Msl1 is a substrate for Msl2 E3 ubiquitin ligase activity. ChIP experiments revealed that Msl1 dimerization is essential for targeting and spreading of the MSL complex on X-linked genes; however, Msl1 binding to promoters of male and female cells is independent of the dimer status and other MSL proteins. Finally, we show that loss of Msl1 dimerization leads to male-specific lethality. We propose that Msl1-mediated dimerization of the entire MSL complex is required for Msl2 binding, X chromosome recognition, and spreading along the X chromosome. Msl1-mediated dimerization of the dosage compensation complex is essential for male X-chromosome regulation in Drosophila.,Hallacli E, Lipp M, Georgiev P, Spielman C, Cusack S, Akhtar A, Kadlec J Mol Cell. 2012 Nov 30;48(4):587-600. doi: 10.1016/j.molcel.2012.09.014. Epub 2012, Oct 18. PMID:23084835[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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