Does a 17 year old have the legal right to sign over the deed to real estate?

NO. The age of majority is 18 in Texas. A minor lacks capacity to own real estate or to sign contracts. Whoever wrote the will should have also included a testamentary trust, and the trustee would have held the property until a time designated in the will, and could have disposed of it if it was in the minor's best interest. The alternative would have been a living trust.
Back to the actual question, through the probate of the will, the court will need to name a conservator or other person to hold the property with legal authority until the minor attains the age of majority.
NOTE: I'm from New England and you should check a Texas attorney. I'm only providing this for informational purposes because your question has been unanswered for a while.

A minor lacks capacity to own real estate or to sign contracts. The age of majority is 18 in Texas. Check with a lawyer in your locale to discuss more of the details.

Good luck to you.

God bless.

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