tRNA splicing in yeast and wheat germ. A cyclic phosphodiesterase implicated in the metabolism of ADP-ribose 1",2"-cyclic phosphate
1994
Culver, G.M. | Consaul, S.A. | Tycowski, K.T. | Filipowicz, W. | Phizicky, E.M.
Adenosine diphosphate (ADP)-ribose 1'',2''-cyclic phosphate (Appr>p) is produced as a result of transfer RNA (tRNA) splicing in the yeast Saccharomyces cerevisiae and probably in other eukaryotes. Endonucleolytic cleavage and ligation result in a mature length tRNA with a 2'-phosphate at the splice junction. This 2'-phosphate is transferred to NAD to produce Appr>p. Metabolism of Appr>p requires hydrolysis of the 1",2"-cyclic phosphate linkage. We show here that yeast has a unique cyclic phosphodiesterase that can hydrolyze Appr>p, ribose 1,2-cyclic phosphate, and ribose 1,3-cyclic phosphate to the corresponding ribose 1-phosphate derivatives. The cyclic phosphodiesterase is highly specific for Appr>p; there is 20-fold less activity on ribose 1,3-cyclic phosphate and no detectable activity on nucleoside 2',3'-cyclic phosphates. A similar cyclic phosphodiesterase is present in wheat germ. The wheat germ cyclic phosphodiesterase activity co-chromatographs with a 2',3'-cyclic nucleotide 3'-phosphodiesterase that was previously identified and purified. The purified wheat germ enzyme has a distinct preference for App>p and ribose cyclic phosphate compared to guanosine 2',3'-cyclic phosphate and shares other biochemical characteristics with the yeast enzyme.
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