Cell polarity is a defining feature of filamentous fungal growth. However, the complete molecular pathway that regulates this morphogenetic characteristic has not yet been elucidated. In Aspergillus nidulans, a germ tube emerges from a discrete location along the conidium following a brief period of isotropic swelling. Plasma membrane and cell wall components are continuously added to the apex of the germ tube via microtubule and actin mediated trafficking of vesicles to this region. As growth progresses, germ tube cells undergo cytokinesis and are compartmentalized by septa. Additionally, the cell wall becomes increasingly cross-linked throughout subapical regions forming a hypha, which continues to grow in the same polarized manner. ANID_05595.1 is located on chromosome 5, contig 96, and encodes a 946 amino acid hypothetical involucrin repeat protein. To investigate the function of ANID_05595.1 in A. nidulans, deletion mutants were generated using pyrGfrom Aspergillus fumigatus as a selectable marker. This mutation resulted in restricted colony growth, increased hyphal diameter, and dichotomous hyphal branching patterns. These phenotypes suggest that ANID_05595.1 function is important to the maintenance of polarized cell growth in A. nidulans and other ascomycetes. The hypothetical ANID_05595.1 protein shares characteristics with Saccharomyces cerevisiae Pea2, a polarisome component required for bipolar budding and mating. Along with structural similarities, the phenotypes observed in S. cerevisiaeDPea2 are similar to A. nidulansD5595. This suggests that ANID_05595.1 may perform a similar mechanistic function to Pea2 in A. nidulans.
Full conference title:
27th Fungal Genetics Conference
- Fungal Genetics Conference 27th (2013)