EXPRESSION OF THE 2 MAIZE TATA-BINDING PROTEIN GENES AND FUNCTION OF THE ENCODED TBP PROTEINS BY COMPLEMENTATION IN YEAST

A single gene encodes the TATA binding protein (TBP) in yeasts and ani mals. Although two TBP-encoding genes (Tbp) previously were isolated f rom both Arabidopsis and maize, the expression and in vivo function of the encoded plant TBPs were not investigated. Here, we report that th e two highly conserved maize Tbp genes are unlinked and reside within larger, ancestrally duplicated segments in the genome. We find quantit ative differences in Tbp1 versus Tbp2 transcript accumulation in some maize tissues. These nonidentical expression patterns may indicate dif ferences in the tissue-specific regulation of these genes, which might allow the two encoded maize TBP isoforms to perform nonoverlapping fu nctions in the plant. In addition, we show that the maize TBP products , unlike animal TBPs, are functionally interchangeable with yeast TBP for conferring yeast cell viability. This is a conclusive demonstratio n of in vivo activity for a nonyeast TBP protein, and these complement ation results point to particular amino acids in TBP that are likely t o influence species-specific protein interactions.