Your employer made an error. You should not have been issued a 1099-MISC. Employee bonuses are supposed to be included on the employee's W-2. When you enter your 1099-MISC in the Other Common Income section of TurboTax, one of the follow-up pages is titled "Do one of these Uncommon Situations apply?" Choose the response "My employer reported this extra money on a 1099-MISC but it should have been reported on a W-2", and proceed from there.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.