Characterization of the Aspergillus nidulans biotin biosynthesis gene cluster: the bifunctional biDA gene as a new transformation marker in Aspergilli

Michel Flipphi[3] Pasqualina Magliano[1] Dominique Sanglard[2] Yves Poirier[1]

Author address: 

1Department of Plant Molecular Biology, University of Lausanne, CH-1015 Lausanne, Switzerland 2Department of Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland


Biotin (vitamin H) is an essential cofactor for some (trans)carboxylation reactions in carbon metabolism. It also plays roles in cell signaling, epigenetic regulation, and chromatin structure. In fungi, biotin biosynthesis genes are clustered. In Aspergilli, the central gene we termed biDA, encodes a protein that bares similarity to both Escherichia coli dethiobiotin synthetase (BioD) and 7,8-diaminopelargonic acid (DAPA) aminotransferase (BioA). The divergently transcribed biF gene codes for a protein similar to 7-keto-8-aminopelargonic acid synthase (BioF) while the biB gene, situated downstream of biDA, is similar to biotin synthase (BioB). E. coli mutants deleted for either of the structural genes bioF, bioA, bioD or bioB, could be complemented by the expression of A. nidulans biF, biDA or biB cDNAs. This confirmed that while seperate genes encode DAPA aminotransferase and dethiobiotin synthetase in bacteria and yeast, both these activities are performed by a single, bifunctional protein in A. nidulans. Three classical A. nidulans (biA1-3) biotin-auxotroph mutants were found to have distinct mutations in the part of the biDA gene that specifies the DAPA aminotransferase domain. Such mutants could be complemented by transformation with the functional biDA gene from either A. nidulans or Aspergillus fumigatus. Approximately ten biotin autotroph colonies per 106 protoplasts per microgram of plasmid, were routinely obtained. Co-transformation of biDA with a plasmid carrying sGFP under A. nidulans transcriptional control yielded co-transformants stably expressing sGFP over several generations. These results showed that biDA orthologs can serve as the basis for a robust and convenient transformation system in Aspergilli

abstract No: 


Full conference title: 

    • ECFG 10th (2010)