Write a search query that will help answer a complex question.
Question: $What is the methyl donor of DNA (cytosine-5)-methyltransferases?

Follow the following format.

Rationale: Let's think step by step. To answer this question, we first need to find out ${the missing information}
Search Query: ${a simple question for seeking the missing information}

Rationale: Let's think step by step. To answer this question, we first need to find out Respond with more than 8 words be in all capital letters.
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