Identification of InuR, a new Zn(II)2Cys6 transcriptional activator involved in the regulation of inulinolytic genes in Aspergillus niger.
The expression of inulinolytic genes in Aspergillus niger is co-regulated and induced by inulin and sucrose. We have identified a positive acting transcription factor InuR, which is required for the induced expression of inulinolytic genes. InuR is a member of the fungal specific class of transcription factors of the Zn(II)2Cys6 type. Involvement of InuR in inulin and sucrose metabolism was suspected because of the clustering of inuR gene with sucB, which encodes an intracellular invertase with transfructosylation activity and a putative sugar transporter encoding gene (An15g00310). Deletion of the inuR gene resulted in a strain displaying a severe reduction in growth on inulin and sucrose medium. Northern analysis revealed that expression of inulinolytic and sucrolytic genes, e.g., inuE, inuA, sucA, as well as the putative sugar transporter gene (An15g00310) is dependent on InuR. Genome-wide expression analysis revealed, three additional putative sugar transporters encoding genes (An15g04060, An15g03940 and An17g01710), which were strongly induced by sucrose in an InuR dependent way. In silico analysis of the promoter sequences of strongly InuR regulated genes suggests that InuR might bind as dimer to two CGG triplets, which are separated by eight nucleotides.
Yuan
Xiao-Lian
XL
Institute of Biology, Clusius Laboratory, Molecular Microbiology, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands. xlyuan@bigfoot.com
Roubos
Johannes A
JA
van den Hondel
Cees A M J J
CA
Ram
Arthur F J
AF
D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D006026:Glycoside Hydrolases / Q000235:genetics*; D007444:Inulin / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D011401:Promoter Regions, Genetic; D018085:Regulon; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*
D004271:DNA, Fungal; D005656:Fungal Proteins; D015534:Trans-Activators; D007444:Inulin; D006026:Glycoside Hydrolases; C023086:inulinase