title: Functional analysis of the transcriptional activator XlnR from Aspergillus niger.
abstract: The transcriptional activator XlnR from Aspergillus niger is a zinc binuclear cluster transcription factor that belongs to the GAL4 superfamily. Several putative structural domains in XlnR were predicted using database and protein sequence analysis. Thus far, only the functionality of the N-terminal DNA-binding domain has been determined experimentally. Deletion mutants of the xlnR gene were constructed to localize the functional regions of the protein. The results showed that a putative C-terminal coiled-coil region is involved in nuclear import of XlnR. After deletion of the C-terminus, including the coiled-coil region, XlnR was found in the cytoplasm, while deletion of the C-terminus downstream of the coiled-coil region resulted in nuclear import of XlnR. The latter mutant also showed increased xylanase activity, indicating the presence of a region with an inhibitory function in XlnR-controlled transcription. Previous findings had already shown that a mutation in the XlnR C-terminal region resulted in transcription of the structural genes under non-inducing conditions. A regulatory model of XlnR is presented in which the C-terminus responds to repressing signals, resulting in an inactive state of the protein.
authors.affiliation: Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
authors.forename: Alinda A
authors.initials: AA
authors.lastname: Hasper
authors.affiliation: Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Trindade
authors.affiliation: Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
authors.forename: Douwe
authors.initials: D
authors.lastname: van der Veen
authors.affiliation: Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
authors.forename: Albert J J
authors.initials: AJJ
authors.lastname: van Ooyen
authors.affiliation: Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
authors.forename: Leo H
authors.initials: LH
authors.lastname: de Graaff
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C115443:XlnR protein, Aspergillus; D049452:Green Fluorescent Proteins