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Schmidtmann, Elisabeth; Anton, Tobias; Rombaut, Pascaline; Herzog, Franz ORCID: 0000-0001-8270-1449; Leonhardt, Heinrich (2016): Determination of local chromatin composition by CasID. In: Nucleus, Vol. 7, No. 5: pp. 476-484
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Abstract

Chromatin structure and function are determined by a plethora of proteins whose genome-wide distribution is typically assessed by immunoprecipitation (ChIP). Here, we developed a novel tool to investigate the local chromatin environment at specific DNA sequences. We combined the programmable DNA binding of dCas9 with the promiscuous biotin ligase BirA* (CasID) to biotinylate proteins in the direct vicinity of specific loci. Subsequent streptavidin-mediated precipitation and mass spectrometry identified both known and previously unknown chromatin factors associated with repetitive telomeric, major satellite and minor satellite DNA. With super-resolution microscopy, we confirmed the localization of the putative transcription factor ZNF512 at chromocenters. The versatility of CasID facilitates the systematic elucidation of functional protein complexes and locus-specific chromatin composition.