Molecular characterization of the Aspergillus nidulans fbxA encoding an F-box protein involved in xylanase induction

• Published in: Fungal genetics and biology Vol. 49; no. 2; pp. 130 - 140
• Main Authors: Colabardini, Ana Cristina, Humanes, Ana Carolina, Gouvea, Paula Fagundes, Savoldi, Marcela, Goldman, Maria Helena S., Kress, Marcia Regina von Zeska, Bayram, Özgür, Oliveira, Juliana Velasco de Castro, Gomes, Marcelo Damário, Braus, Gerhard H., Goldman, Gustavo Henrique
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2012
• Subjects: Aspergillus nidulans; Aspergillus nidulans - genetics; Aspergillus nidulans - metabolism; carbon; Catabolite repression; Catabolite Repression - genetics; CreA; Deoxyglucose - metabolism; Endo-1,4-beta Xylanases - genetics; Endo-1,4-beta Xylanases - metabolism; eukaryotic cells; F-box proteins; F-Box Proteins - genetics; F-Box Proteins - metabolism; Fungal Proteins - genetics; Fungal Proteins - metabolism; fungi; genes; glucose; messenger RNA; mutants; S-Phase Kinase-Associated Proteins - genetics; S-Phase Kinase-Associated Proteins - metabolism; Sequence Deletion; Trans-Activators - genetics; Trans-Activators - metabolism; transcription (genetics); transcription factors; Ubiquitination; XlnR; xylan; Xylanase; xylanases; Xylans - metabolism; xylose; Xylose - metabolism; XlnR; Catabolite repression; CreA; Xylanase; Aspergillus nidulans; F-box proteins
• ISSN: 1087-1845; 1096-0937
• DOI: 10.1016/j.fgb.2011.11.004

► Forty-two A. nidulans F-box null mutants screened for resistance to 2-deoxy-d-glucose. ► ΔfbxA is involved in xylanase induction and carbon catabolite repression (CCR). ► FbxA contains a functional F-box domain that binds to Skp1 of SCF-type ligase. ► The ΔfbxA mutant interacts genetically with creAd-30, creB15, and creC27. ► FbxA provides another layer of complexity to CCR in filamentous fungi. The filamentous fungus Aspergillus nidulans has been used as a fungal model system to study the regulation of xylanase production. These genes are activated at transcriptional level by the master regulator the transcriptional factor XlnR and repressed by carbon catabolite repression (CCR) mediated by the wide-domain repressor CreA. Here, we screened a collection of 42 A. nidulans F-box deletion mutants grown either in xylose or xylan as the single carbon source in the presence of the glucose analog 2-deoxy-d-glucose, aiming to identify mutants that have deregulated xylanase induction. We were able to recognize a null mutant in a gene (fbxA) that has decreased xylanase activity and reduced xlnA and xlnD mRNA accumulation. The ΔfbxA mutant interacts genetically with creAd-30, creB15, and creC27 mutants. FbxA is a novel protein containing a functional F-box domain that binds to Skp1 from the SCF-type ligase. Blastp analysis suggested that FbxA is a protein exclusive from fungi, without any apparent homologs in higher eukaryotes. Our work emphasizes the importance of the ubiquitination in the A. nidulans xylanase induction and CCR. The identification of FbxA provides another layer of complexity to xylanase induction and CCR phenomena in filamentous fungi.