Penicillium marneffei like many other pathogenic species of fungi is dimorphic. At 25Â° C, P. marneffei exhibits filamentous growth morphology, reproducing through the production of asexual spores borne on conidiophores. At 37Â°C a yeast-like growth form replaces the filamentous morphology with single cells reproducing via fission. This form is pathogenic, and is associated with many cases of human and animal infection. Here we describe the cloning and characterisation of a P. marneffei gene which encodes an ATTS DNA binding domain protein - PmabaA. In Aspergillus nidulans, AbaA (an ATTS protein) regulates development of sporogenous cells during conidiation. In Saccharomyces cerevisiae, Teclp, an AbaA homologue regulates pseudohyphal development. This implies a conserved role for ATTS proteins in regulating fungal development systems. A P. marneffei homologue may also have a regulatory role during development in this species, perhaps during dimorphic growth. PmabaA was therefore cloned via low stringency hybridisation to the A. nidulans abaA gene. A high level of homology between the two is apparent at the protein level, with complete conservation of the DNA binding motif. Amino acid conservation is limited at the C-termini of the proteins and may suggest functional divergence in the P. marneffei homologue however it is able to complement the abaA mutation in A. nidulans indicating functional conservation. A transformation protocol for this fungus was developed and enabled the creation of a PmabaA mutant by targeted deletion. The aconidial mutant phenotype at 25 Â°C indicates that PmabaA, like its A. nidulans homologue plays a crucial role in regulating cellular morphogenesis. The cloned abaA genes from both P. marneffei and A. nidulans complement the mutant phenotype, indicating functional interchangeability between the two proteins in vivo.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)