When one stage door closes, another one opens. Mark and Leslie Nolte of Iowa City are transforming the former home of Riverside Theatre, at 213 N. Gilbert St., into The James Theater. By the start of the next school year, they hope to throw open the doors to new a community performing arts center, as well as a performance and workshop site for the Iowa Conservatory, a performing arts high school being incubated at Nolte Academy in Coralville.