AUTOREGULATION MAY CONTROL THE EXPRESSION OF YEAST PYRUVATE DECARBOXYLASE STRUCTURAL GENES PDC1 AND PDC5

作者：HOHMANN S^*; CEDERBERG H

来源：European Journal of Biochemistry, 1990, 188(3): 615-621.

DOI：10.1111/j.1432-1033.1990.tb15442.x

<jats:p>Recently we deleted the pyruvate decarboxylase structural gene <jats:italic>PDC1</jats:italic> from the genome of the yeast <jats:italic>Saccharomyces cerevisiae</jats:italic>. The <jats:italic>pdc1</jats:italic> deletion mutants had pyruvate decarboxylase activity due to the presence of a second structural gene [Schaaff, I., Green, J. B. A., Gozalbo, D. &amp; Hohmann, S. (1989) <jats:italic>Curr. Genet. 15</jats:italic>, 75–81]. We cloned and sequenced this gene which we call <jats:italic>PDC5</jats:italic>. The predicted amino acid sequences of <jats:italic>PDC1</jats:italic> and <jats:italic>PDC5</jats:italic> are 88% identical.</jats:p><jats:p>Deletion of <jats:italic>PDC5</jats:italic> did not cause any decrease in the specific pyruvate decarboxylase activity while <jats:italic>pdc1</jats:italic> deletion mutants had 80% of the wild‐type activity. Deletion mutants lacking both <jats:italic>PDC1</jats:italic> and <jats:italic>PDC5</jats:italic> did not show any detectable pyruvate decarboxylase activity <jats:italic>in vitro</jats:italic> and were unable to ferment glucose. This indicates that <jats:italic>PDC1</jats:italic> and <jats:italic>PDC5</jats:italic> are the only structural genes for pyruvate decarboxylase in yeast.</jats:p><jats:p>The <jats:italic>PDC5</jats:italic> isoenzyme showed a slightly higher <jats:italic>K</jats:italic><jats:sub>m</jats:sub> value for its substrate pyruvate than the <jats:italic>PDC1</jats:italic> product (<jats:italic>PDC5: K</jats:italic><jats:sub>m</jats:sub>= 8 mM; <jats:italic>PDC1</jats:italic>: <jats:italic>K</jats:italic><jats:sub>m</jats:sub>= 5 mM), as measured in crude extract of <jats:italic>pdc1</jats:italic> and <jats:italic>pdc5</jats:italic> deletion mutants, respectively.</jats:p><jats:p> <jats:italic>PDC5</jats:italic> is only expressed in <jats:italic>pdc1</jats:italic> deletion mutants. No mRNA transcribed from <jats:italic>PDC5</jats:italic> could be detected in wild‐type cells. Thus, in addition to the control by glucose induction, pyruvate decarboxylase activity seems to be subject to autoregulation. Similar phenomena have been described previously for tubulin, histones and a ribosomal protein but not for metabolic enzymes.</jats:p>

• 出版日期1990-3-30