Characterization and lysine control of expression of the lys1 gene of Penicillium chrysogenum encoding homocitrate synthase.
A 2071-bp DNA fragment, containing a gene (lys1) encoding a protein that showed 71.1% identical amino acids with the Yarrowia lipolytica homocitrate synthase and 71.7% identity with the Saccharomyces cerevisiae homologous enzyme, was cloned from a genomic library of Penicillium chrysogenum. The lys1 gene contained three introns and encoded a protein of 474 amino acids with a deduced molecular mass of 52kDa. lys1 was located in chromosome II (9.6Mb) in the wild-type P. chrysogenum NRRL 1951, whereas it hybridized with chromosome III (7.5Mb) in the high penicillin production strain AS-P-78. The lys1 gene is transcribed as a monocistronic transcript of 2.0kb. Levels of the lys1 transcript were high in P. chrysogenum Wis 54-1255 cultures in defined penicillin production medium at 24 and 48h, coinciding with the rapid growth phase, but clearly decreased during the penicillin production phase, suggesting that alpha-aminoadipic acid formation for penicillin biosynthesis may be limited at the homocitrate synthase level. Expression of lys1 was partially repressed by high concentrations of lysine in the culture medium, but lysine repression seems to be a weak mechanism of control of the lysine pathway as compared to lysine inhibition of homocitrate synthase.
Bañuelos
O
O
Area of Microbiology, Faculty of Biology, University of León, 24071, León, Spain.
Casqueiro
J
J
Fierro
F
F
Hijarrubia
M J
MJ
Gutiérrez
S
S
Martín
J F
JF
D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018628:Gene Dosage; D015966:Gene Expression Regulation, Fungal; D008239:Lysine / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D007652:Oxo-Acid-Lyases / Q000235:genetics* / Q000378:metabolism; D010408:Penicillium chrysogenum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D005656:Fungal Proteins; C021365:homocitrate synthase; D007652:Oxo-Acid-Lyases; D008239:Lysine