Aspergillus nidulans
Role of COG Proteins in Morphogenesis

The swoP1 mutation was discovered in a screen for temperature-sensitive morphological mutants in A. nidulans.  Mutants have impaired polarity establishment during spore germination at restrictive temperature.

The gene has been cloned and shown to be an orthologue of COG4, a component of the Golgi apparatus COG (Conserved Oligomeric Golgi) vesicle tethering complex.  The swoP1 mutant allele is predicted to lack the last 55 amino acids at the C terminal.   Under the direction of Sara Gremillion (Armstrong State University) and in collaboration with Steve Harris (University of Nebraska), we have characterized the phenotype of the swoP1 mutant along with that of the related podB1 mutant in COG2. (Gremillion et al., 2014)

By overexpressing known A. nidulans COG orthologues in swoP1 (COG4-defective) or podB1 (COG2-defective) mutant backgrounds, Sara has shown genetic interactions between COG4 and COG2 (over-expression of either can complement the other's phenotype) and between COG3 and COG2.  Over-expression of COG3 complements the podB1 (COG2-defective) phenotype, but not that of swoP1.  Overexpression of the remaining COG orthologues (COG1, COG6, and COG6) is without effect on either mutation.  These results are consistent with proposed structures of the "A-lobes" of yeast and mammalian COGs.

GFP chimeras of COG2 and COG4 demonstrate localization of each protein to subcellular compartments consistent with the fungal Golgi apparatus (see below).


Gremillion, S. K., S. D. Harris, L. Jackson-Hayes, S. G. W. Kaminskyj, D. M. Loprete, A. C. Gauthier, S. Mercer, A. J. Ravita, and T. W. Hill.   2014.  "Mutations in proteins of the Conserved Oligomeric Golgi complex affect polarity, cell wall structure, and glycosylation in the filamentous fungus Aspergillus nidulans."  Fungal Genetics & Biology 73: 69-82.

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