Functional analysis of the transcriptional activator XlnR from Aspergillus niger.
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.
Hasper
Alinda A
AA
Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
Trindade
Luisa M
LM
Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
van der Veen
Douwe
D
Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
van Ooyen
Albert J J
AJJ
Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
de Graaff
Leo H
LH
Fungal Genomics section, Laboratory of Microbiology, Wageningen University, Dreijenlaan 2, NL-6703 HA Wageningen, The Netherlands.
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
D005656:Fungal Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C115443:XlnR protein, Aspergillus; D049452:Green Fluorescent Proteins