CreA mediates repression of the regulatory gene xlnR which controls the production of xylanolytic enzymes in Aspergillus nidulans.
The Aspergillus nidulans xlnR gene encodes a Zn(2)Cys(6) transcription activator necessary for the synthesis of the main xylanolytic enzymes, i.e. endo-xylanases X(22), X(24) and X(34), and beta-xilosidase XlnD. Expression of xlnR is not sufficient for induction of genes encoding the xylanolytic complex, the presence of xylose is absolutely required. It has been established previously that the wide-domain carbon catabolite repressor CreA indirectly represses xlnA (encodes X(22)) and xlnB (encodes X(24)) genes as well as exerting direct repression on xlnA. This work provides evidence that CreA-mediated indirect repression occurs through repression of xlnR: (i) the xlnR gene promoter is repressed by glucose and this repression is abolished in creA(d)30 mutant strains and (ii) deregulated expression of xlnR completely relieves glucose repression of xlnA and xlnB. Thus, CreA and XlnR form a transcriptional cascade regulating A. nidulans xylanolytic genes.
Tamayo
Elsy N
EN
Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Apartado de Correos 73, 46100 Burjassot, Valencia, Spain.
Villanueva
Adela
A
Hasper
Alinda A
AA
de Graaff
Leo H
LH
Ramón
Daniel
D
Orejas
Margarita
M
D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D001234:Aspergillus niger / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D015536:Down-Regulation; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism*; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014995:Xylosidases / Q000235:genetics* / Q000378:metabolism
D005656:Fungal Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; C115443:XlnR protein, Aspergillus; C071237:CreA protein, Aspergillus nidulans; D014995:Xylosidases; D005947:Glucose