Inactivation of the lys7 gene, encoding saccharopine reductase in Penicillium chrysogenum, leads to accumulation of the secondary metabolite precursors piperideine-6-carboxylic acid and pipecolic acid from alpha-aminoadipic acid.
Pipecolic acid serves as a precursor of the biosynthesis of the alkaloids slaframine and swainsonine (an antitumor agent) in some fungi. It is not known whether other fungi are able to synthesize pipecolic acid. Penicillium chrysogenum has a very active alpha-aminoadipic acid pathway that is used for the synthesis of this precursor of penicillin. The lys7 gene, encoding saccharopine reductase in P. chrysogenum, was target inactivated by the double-recombination method. Analysis of a disrupted strain (named P. chrysogenum SR1-) showed the presence of a mutant lys7 gene lacking about 1,000 bp in the 3'-end region. P. chrysogenum SR1- lacked saccharopine reductase activity, which was recovered after transformation of this mutant with the intact lys7 gene in an autonomously replicating plasmid. P. chrysogenum SR1- was a lysine auxotroph and accumulated piperideine-6-carboxylic acid. When mutant P. chrysogenum SR1- was grown with L-lysine as the sole nitrogen source and supplemented with DL-alpha-aminoadipic acid, a high level of pipecolic acid accumulated intracellularly. A comparison of strain SR1- with a lys2-defective mutant provided evidence showing that P. chrysogenum synthesizes pipecolic acid from alpha-aminoadipic acid and not from L-lysine catabolism.
Naranjo
Leopoldo
L
Area de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, 24071 León, Spain.
Martín de Valmaseda
Eva
E
Casqueiro
Javier
J
Ullán
Ricardo V
RV
Lamas-Maceiras
Mónica
M
Bañuelos
Oscar
O
Martín
Juan F
JF
D015074:2-Aminoadipic Acid / Q000378:metabolism*; D002264:Carboxylic Acids / Q000378:metabolism; D003470:Culture Media; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D008239:Lysine / Q000378:metabolism; D010408:Penicillium chrysogenum / Q000201:enzymology* / Q000235:genetics; D010875:Pipecolic Acids / Q000378:metabolism*; D012443:Saccharopine Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic
D002264:Carboxylic Acids; D003470:Culture Media; D005656:Fungal Proteins; D010875:Pipecolic Acids; D015074:2-Aminoadipic Acid; D012443:Saccharopine Dehydrogenases; D008239:Lysine