The powers of a district created pursuant to this chapter shall be exercised by a commission. The commission shall consist of four members of the governing body, appointed by the governing body, plus one member of the town council of any participating town, appointed by the town council of the participating town. In addition to the appointed members, the Chairman of the Commonwealth Transportation Board or his designee shall be a member of the commission of any district created pursuant to this chapter. The commission shall elect a chairman from its membership. The chairman may be the chairman or presiding officer of the governing body. In addition, the commission, with the advice of the district advisory board, shall elect a secretary and a treasurer, who may be members or employees of the governing body, the town council of a participating town, or other governmental body. The offices of secretary and treasurer may be combined. A majority of the commission members shall constitute a quorum, and a majority vote shall be necessary for any action taken by the commission. No vacancy in the membership of the commission shall impair the right of a majority of the members to form a quorum or to exercise all of its rights, powers, and duties.