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Fungal Genet Biol. 2003 Mar;38(2):228-36.

Expression of the mnpA gene that encodes the mannoprotein of Aspergillus nidulans is dependent on fadA and flbA as well as veA.

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Division of Biological Sciences, Basic Science Research Institute, Chonbuk National University, Chonju, 561-756, Chonbuk, Republic of Korea.


The single copy mnpA gene that encodes a mannoprotein of Aspergillus nidulans and its cDNA were isolated from the genomic and cDNA libraries, respectively. The determined nucleotide sequences of the genomic DNA and its cDNA revealed that the gene has an open-reading frame of 261 amino acids without introns. The deduced amino acid sequence showed a 60% identity to that of Aspegillus fumigatus galactomannoprotein MP1. The mnpA gene was expressed more abundantly in the wild-type than in the veA-null mutant. It was expressed at a lower level in fadA-null mutants, veA(+) or veA1 (regardless of their genetic background), than in the fadA(+) strain. However, the expression level was slightly higher in the veA(+) DeltafadA strain than in the veA1 DeltafadA strain. Furthermore, the amount of the mnpA transcript was higher in the flbA(+) strain than in the flbA-null mutant. These results indicate that the fadA and flbA genes in addition to the veA gene are necessary for the mnpA expression. The mnpA gene was expressed highly in vegetative mycelia and at a reduced level in sexual structures, but not in conidia. Its expression was almost constitutive during asexual development up to 18h after the transfer of mycelial balls onto a solid medium, and decreased thereafter. During sexual development, its expression reached its maximum 0-20h after the induction of sexual development, and then decreased thereafter. The mnpA-null mutant, that was still viable, showed no phenotypic difference in development, growth rate, protein secretion, and germination of both the ascospores and conidia from the wild-type. This suggests that the mannoprotein that is encoded by the mnpA gene is dispensable.

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