President Boris Yeltsin appointed Mikhail Komissar, director general of the Interfax news agency, as deputy head of the presidential administration Thursday. Komissar replaced Maxim Boiko, who became deputy prime minister and chairman of the Russian State Property Committee on Wednesday. The appointment puts Komissar in charge of relations with political parties, public organizations and mass media. Komissar, 44, is one of the founders of the agency and has led it since 1989. The agency said that he submitted a letter to the Interfax board of directors Thursday, saying he will take a leave of absence while he serves in the presidential administration. Komissar was part of a team of Soviet foreign broadcast radio journalists who started the first private Russian news agency with several fax machines in 1989. Since then, it has grown to become a leading Russian new agency, competing with the state-owned Itar-Tass giant.