title: Transcriptional upregulation of four genes of the lysine biosynthetic pathway by homocitrate accumulation in Penicillium chrysogenum: homocitrate as a sensor of lysine-pathway distress.
abstract: The lysine biosynthetic pathway has to supply large amounts of alpha-aminoadipic acid for penicillin biosynthesis in Penicillium chrysogenum. In this study, we have characterized the P. chrysogenum L2 mutant, a lysine auxotroph that shows highly increased expression of several lysine biosynthesis genes (lys1, lys2, lys3, lys7). The L2 mutant was found to be deficient in homoaconitase activity since it was complemented by the Aspergillus nidulans lysF gene. We have cloned a gene (named lys3) that complements the L2 mutation by transformation with a P. chrysogenum genomic library, constructed in an autonomous replicating plasmid. The lys3-encoded protein showed high identity to homoaconitases. In addition, we cloned the mutant lys3 allele from the L2 strain that showed a G(1534) to A(1534) point mutation resulting in a Gly(495) to Asp(495) substitution. This mutation is located in a highly conserved region adjacent to two of the three cysteine residues that act as ligands to bind the iron-sulfur cluster required for homoaconitase activity. The L2 mutant accumulates homocitrate. Deletion of the lys1 gene (homocitrate synthase) in the L2 strain prevented homocitrate accumulation and reverted expression levels of the four lysine biosynthesis genes tested to those of the parental prototrophic strain. Homocitrate accumulation seems to act as a sensor of lysine-pathway distress, triggering overexpression of four of the lysine biosynthesis genes.
authors.affiliation: Área de Microbiología, Departamento de Biología Molecular, Facultad de CC. Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 Leon, Spain.
authors.forename: Franco
authors.initials: F
authors.lastname: Teves
authors.affiliation: Área de Microbiología, Departamento de Biología Molecular, Facultad de CC. Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 Leon, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Lamas-Maceiras
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: García-Estrada
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.|Área de Microbiología, Departamento de Biología Molecular, Facultad de CC. Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 Leon, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Casqueiro
authors.affiliation: Área de Microbiología, Departamento de Biología Molecular, Facultad de CC. Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 Leon, Spain.
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Naranjo
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.
authors.forename: Ricardo V
authors.initials: RV
authors.lastname: Ullán
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.
authors.forename: José-Martín
authors.initials: JM
authors.lastname: Scervino
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Wu
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.
authors.forename: Tania
authors.initials: T
authors.lastname: Velasco-Conde
authors.affiliation: Instituto de Biotecnología de León (INBIOTEC), Parque Científico de León, Av. Real, 1, 24006 León, Spain.|Área de Microbiología, Departamento de Biología Molecular, Facultad de CC. Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 Leon, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Martín
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D006836:Hydro-Lyases / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000096:biosynthesis*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010408:Penicillium chrysogenum / Q000235:genetics* / Q000378:metabolism*; D017354:Point Mutation; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic; D014233:Tricarboxylic Acids / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D014233:Tricarboxylic Acids; C028143:homocitric acid; D006836:Hydro-Lyases; C107855:homoaconitate hydratase; D008239:Lysine