Robert Aubry Davis is not painfully shy. He does pledge breaks for Washington’s WETA-TV, after all. For the winter holidays, local media report, Davis will follow in the large and dainty footsteps of Harvey Fierstein to perform the motherly role of Edna Turnblad in the Tony-Award-winning musical version of John Waters’ “Hairspray,” opening Nov. 21 at the highly touted Signature Theater, just down the street from WETA’s headquarters in Arlington, Va. The late drag spectacle Divine originated the role in Waters’ earlier movie. Davis, a longtime WETA-FM personality and now a deejay on Sirius XM Satellite Radio, also hosts and produces Millenium of Music, the program of pre-Baroque works syndicated to many pubradio stations and aired on Sirius XM and Radio Netherlands Worldwide. The production is scheduled to run through Jan. 29.