The 316th prohibition is that we are forbidden from cursing a Nasi.1
The source of this prohibition is G‑d's statement2 (exalted be He), "A Nasi of your people do not curse."
The term Nasi is used in Scripture to refer to a king who has ruling authority, as in G‑d's statement,3 "If the Nasi sins..." As used in the words of our Sages, it refers solely to the head of the 70-member Sanhedrin. Throughout the Talmud and Mishneh we find mention of, "Nesi'im and heads of the High Court"; "Nasi and head of the High Court."4 Our Sages also said,5 "If a Nasi wants to overlook his honor, his honor may be overlooked. If a king wants to overlook his honor, his honor may not be overlooked."6
You should be aware that this prohibition includes both the Nasi [mentioned in the Talmud] and the king. The mitzvah comes to prohibit cursing anyone who is in the highest position of authority, regardless of whether his authority is in rulership [i.e., the king] or in Torah, i.e. the Yeshivah. This is apparent from the detailed description of this mitzvah.
One who transgresses this prohibition is punished with lashes.