A person, or his or her or dependent child, spouse, of any person, who is, or has been in the past one year, in the employ of or holding any official relation to any company subject to the supervision of the commission, or engaged in the management of the company, or owning stock, bonds, or other securities thereof, or who is, or has been in the past one year, in any manner, connected with the operation of the company in this state, shall not be a commissioner or clerk of the commission; nor shall any commissioner or clerk of the commission, personally or in connection with a partner or agent, render professional service for or against or make or perform any business contract with any company subject to the supervision, relating to the business of the company, except contracts made with them as common carriers, or in regular course of public service.