Flexibility in crosstalk between H2B ubiquitination and H3 methylation in vivo

Histone H2B ubiquitination is a dynamic modification that promotes methylation of histone H3K79 and H3K4. This crosstalk is important for the DNA damage response and has been implicated in cancer. Here, we show that in engineered yeast strains, ubiquitins tethered to every nucleosome promote H3K79 and H3K4 methylation from a proximal as well as a more distal site, but only if in a correct orientation. This plasticity indicates that the exact location of the attachment site, the native ubiquitin‐lysine linkage and ubiquitination cycles are not critical for trans‐histone crosstalk in vivo . The flexibility in crosstalk also indicates that other ubiquitination events may promote H3 methylation. Synopsis Variously tethered ubiquitins, expressed as linear histone‐ubiquitin fusions, can substitute for native H2BK123ub in the crosstalk to H3 methylation and in the DNA damage response. This reveals a remarkable plasticity in H2Bub signaling in vivo . Ubiquitins tethered to the N‐terminus of H2A efficiently bypass native H2B ubiquitination in promoting H3K79 and H3K4 methylation. Ubiquitin tethered to the C‐terminus of H2B, on the same region of the nucleosome but in the opposite orientation, confers only modest crosstalk. Tethered ubiquitins support the DNA damage response following UV irradiation. Graphical Abstract Variously tethered ubiquitins, expressed as linear histone‐ubiquitin fusions, can substitute for native H2BK123ub in the crosstalk to H3 methylation and in the DNA damage response. This reveals a remarkable plasticity in H2Bub signaling in vivo .