title: Constitutive over-expression of pectinases in Penicillium occitanis CT1 mutant is transcriptionally regulated.
abstract: The CT1 mutant of Penicillium occitanis hyperproduces extracellular pectinases constitutively since it secretes pectinases even on glucose-containing medium. We show here that all other hydrolytic enzymes remain at low activities in CT1, confirming the specificity of the regulatory mutation towards pectinases. We isolated, by RT-PCR and through the construction of a cDNA library, three fragments coding for: a pectin lyase (pnl1), a polygalacturonase (pga1) and a pectate lyase (pal1). These fragments were used as probes in Northern blots analysis of the wild type strain CL100 and the CT1 mutant of P. occitanis grown in three culture conditions. The CT1 mutant showed a very high amount of pnl1, pga1 and pal1 mRNA either in pectin, glucose or glycerol grown cells while in the wild type CL100 strain, all transcripts were undetectable even on pectin. These results suggest that the CT1 mutation affects a trans-regulatory transcriptional factor regulating pectinase expression.
authors.affiliation: Laboratory of Biomass Valorisation and Production of Proteins in Eukaryotes, Centre of Biotechnology of Sfax, University of Sfax, Route Sidi Mansour Km 6, P. O. Box 1177, 3018, Sfax, Tunisia.
authors.forename: Malika
authors.initials: M
authors.lastname: Ayadi
authors.forename: Sameh
authors.initials: S
authors.lastname: Trigui
authors.forename: Hèla
authors.initials: H
authors.lastname: Trigui-Lahiani
authors.forename: Noomen
authors.initials: N
authors.lastname: Hadj-Taïeb
authors.forename: Mohamed
authors.initials: M
authors.lastname: Jaoua
authors.forename: Ali
authors.initials: A
authors.lastname: Gargouri
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001709:Biotechnology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D010407:Penicillium / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D011096:Polygalacturonase / Q000235:genetics* / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D014157:Transcription Factors; D011096:Polygalacturonase