Abstract

We characterized three Arabidopsis thaliana cDNA clones that could rescue the sterile phenotype of the Schlzosaccharomyces pombe pde1 mutant, which Is defective In cAMP phosphodlesterase. The first clone had a coding capacity of 399 amlno acids that Is 35% Identical with rat protein phosphatase 2C (PP2C). The second had a coding capacity of 159 amino acids that is 41% Identical with human DM. DM has been shown to Interact with TATA-binding protein (TBP) and block Its ability to activate transcription. The third encoded Arabidopsis TBP Itself. Saccharomyces cerevlslae TBP also could suppress the sterile phenotype If expressed In S.pombe pde1 cells, but overexpression of S.pombe TBP could do so very poorly. These observations suggest preliminarily that PP2C may counteract cAMP-dependent protein klnase in fission yeast cells, and that the heterologous TBPs and DM may interfere with the general transcription factors of S.pombe so that the gene expression in the host cell becomes affirmative of sexual development. Furthermore, the identification of a DM-like protein In A. thaliana strongly argues for the ubiquity of this protein among eukaryotlc genera and for a conserved mechanism to regulate transcription initiation that involves DM.

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