The commissioner shall nominate for appointment by the governor and council a director of economic development and a director of travel and tourism development, each of whom shall serve, subject to the provisions of N.H. Rev. Stat. § 4:1, for a term of 4 years from the date of appointment and until a successor is appointed and qualified. The directors of the divisions of economic development and travel and tourism development who are in office on the effective date of the transfer of those divisions to the department of business and economic affairs shall serve for the remainder their terms, at which time they may be reappointed in accordance with the provisions of this chapter. Any vacancy in such office shall be filled for the unexpired term in the same manner as the original appointment. Directors of divisions shall be responsible for the administration and operation of their respective divisions subject to the supervisory authority of the commissioner as set forth in N.H. Rev. Stat. § 12-O:5.