Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Let me give you an example: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
The answer to this example can be: In what year did francis, duke of anjou leave the netherlands?
Here is why: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.

OK. solve this:
Dot1 is an evolutionarily conserved histone methyltransferase that methylates lysine-79 of histone H3 in the core domain. Unlike other histone methyltransferases, Dot1 does not contain a SET domain, and it specifically methylates nucleosomal histone H3. We have solved a 2.5 A resolution structure of the catalytic domain of human Dot1, hDOT1L, in complex with S-adenosyl-L-methionine (SAM). The structure reveals a unique organization of a mainly alpha-helical N-terminal domain and a central open alpha/beta structure, an active site consisting of a SAM binding pocket, and a potential lysine binding channel. We also show that a flexible, positively charged region at the C terminus of the catalytic domain is critical for nucleosome binding and enzymatic activity. These structural and biochemical analyses, combined with molecular modeling, provide mechanistic insights into the catalytic mechanism and nucleosomal specificity of Dot1 proteins.
Answer:
What is the characteristic domain of histone methyltransferases?