Dean Singleton of Denver, who was replaced as head of MediaNews Group by John Paton earlier this year, is now leaving the chairmanship of the Associated Press board of directors. His five-year term has expired. The AP board has picked Mary Junck, chairman and CEO of Lee Enterprises, as the wire service’s new chairman. One of her first tasks will be to find a replacement for AP president and CEO Tom Curley, who announced earlier this week that he will step down once the board finds a replacement.