IDENTIFICATION AND DISRUPTION OF THE GENE ENCODING THE K-ACTIVATED ACETALDEHYDE DEHYDROGENASE OF SACCHAROMYCES-CEREVISIAE()

The identity of the gene encoding the mitochondrial K+-activated aceta ldehyde dehydrogenase (K+-ACDH) of Saccharomyces cerevisiae has been c onfirmed, The gene is situated on the right arm of chromosome XV, bear s the systematic name YOR374w and the deduced product shows significan t homology to other members of the S. cerevisiae aldehyde dehydrogenas e (ALDH) family. YOR374w has now been assigned the gene name.ALD7. The N-terminal amino acid sequences of K+-ACDHs purified from several div erse strains of S. cerevisiae were determined, and found to have 81-10 0% identity in alignments with the product of ALD7. Haploid mutants co ntaining a deletion of ALD7 were constructed and, in these strains, th e K+-ACDH was not detectable under any growth conditions examined.The activity of the Mg2+-activated acetaldehyde dehydrogenase (Mg2+-ACDH), encoded by ALD6, remained at wild-type levels in the mutants. Growth on glucose was not affected in the mutants lacking ALD7 (in contrast t o the behaviour of ald6 mutants);, whereas growth on ethanol was sever ely impaired. This observation, together with previous work by our gro up, shows that both the Mg2+ and K+-ACDHs are required for growth on e thanol, whilst only the former plays a role during growth on glucose. European , (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.