Impaired growth on glucose of a pyruvate dehydrogenase-negative mutant of Kluyveromyces lactis is due to a limitation in mitochondrial acetyl-coenzyme A uptake

A Kluyveromyces lactis mutant with a disruption in the KlPDA1 gene, encodin g the E1 alpha subunit of the pyruvate dehydrogenase complex, exhibited a f our-fold reduced specific growth rate on glucose in minimal medium. Growth of the Klpda1 mutant on glucose in complex medium was not affected. Its gro wth on defined media could be restored by adding amino acids that require m itochondrial acetyl-CoA for their biosynthesis as nitrogen sources. This, t ogether with the observation that low concentrations of L-carnitine also re stored growth on glucose, indicates that the slow-growth phenotype of the K lpda1 mutant is due to a limited capacity of the mitochondria for import of cytosolic acetyl-CoA. (C) 1999 Federation of European Microbiological Soci eties. Published by Elsevier Science B.V. All rights reserved.