Characterization of the lys7 gene of Penicillium chrysogenum encoding the saccharopine reductase, an enzyme involved in the conversion of pipecolic acid into lysine.
Naranjo
L., Martín de Valmaseda E., Bañuelos O., López
P., Riaño J., Ullán R.V., Casqueiro J. and Martín J.F.
Area of Microbiology, Faculty of Biology and Environmental Sciences, University of León. 24071, León (Spain).
In this work we are showing that pipecolic acid is converted into lysine in P. chrysogenum. As well, is shown that P. chrysogenum can use pipecolic acid as sole nitrogen source, probably by using the pipecolate oxidase, which converts pipecolic acid into piperideine-6-carboxylic acid. We have isolated two mutants named 7.2 and 10.25 unable to use pipecolic acid, these mutants lacked the pipecolate oxidase and saccharopine reductase activity, respectively. The 10.25 mutant was unable to grow in Czapek medium supplement with a-aminoadipic acid. The gene complementing the 10.25 mutant has been cloned, and sequence analysis revealed that the encoded protein has strong homology to the saccharopine reductase from Neurospora crassa, Magnaporthe grisea, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The data showed in this work suggest that, in P. chrysogenum, the conversion of pipecolic acid into lysine proceeds through the conversion of pipecolic acid into piperideine-6-carboxylic acid, saccharopine and lysine, by the consecutive action of pipecolate oxidase, saccharopine reductase and saccharopine dehydrogenase.
