STRUCTURE OF A MAIZE TRYPTOPHAN SYNTHASE ALPHA-SUBUNIT GENE WITH PITHENHANCED EXPRESSION

A cDNA derived from an abundant maize pith mRNA transcript and its cor responding genomic equivalent have been isolated and characterized. Hi gh transcript levels are seen in the pith and young leaves of maize pl ants, while no transcript is detected in seed tissue of any age. The p rotein encoded by the isolated gene has considerable homology with try ptophan synthase alpha subunit (trpA) from other organisms and the cDN A clone can complement an E. coli trpA mutant. These data support the conclusion that this cDNA and the corresponding genomic clone encode a maize trpA protein.