The installation of unnatural amino acids into proteins of living cells is an enabling technology that facilitates an enormous number of applications. UV-activatable crosslinker amino acids allow the formation of a covalent bond between interaction partners in living cells with nearly perfect spatial and temporal control. Here, we describe how this method can be employed to map chromatin interactions and to follow these interactions across the cell cycle in synchronized yeast populations. This method thereby provides unprecedented insights into the molecular events controlling chromatin reorganization in mitosis. As similar tools are available for other organisms, it should be possible to derive similar strategies for these and for other synchronizable processes.
Keywords: Cell cycle; Chromatin; Genetic code expansion; Histones; Mitosis; Noncanonical amino acids; UV-crosslinking.