Dot1 (disruptor of telomeric silencing-1, DOT1L in human) is the only enzyme required to histone H3 lysine 79 methylation (H3K79me), and evolutionarily conserved in most eukaryotes. Although Dot1p is well-known to participate in the regulation of gene silencing near telomeres via H3 K79 methylation in Saccharomyces cerevisiae, it is unclear the reason why H3 K79 methylation is highly distributed in most euchromatic genes, and the role and molecular mechanism of Dot1p in euchromatin. In this talk, I will discuss the recent progress of our laboratory about chromatin dynamics by Dot1p. Our recent work identified a novel role of Dot1p that controls histone exchange through non-canonical function of Dot1p, and provides new insights into how histone modifying protein can regulate chromatin stability in budding yeast.