The COG (conserved oligomeric Golgi) complex is associated with tethering of vesicles undergoing retrograde transport within the Golgi apparatus. Studies in animals and yeast revealed that the COG complex is composed of eight protein subunits which form a bilobed structure. In both models, the lobe containing COG1-4 is essential for proper COG function. Little is known of the COG complex in the filamentous fungi. Two temperature sensitive mutants have been discovered in Aspergillus nidulans, named swoP1 (swollen cell) and podB1 (polarity defective). Both mutants display abnormal spore swelling and polarity when grown at a restrictive temperature. Genes complementing the mutations of swoP1 and podB1 have sequence homology to COG4 (ANID7462.1) and a conserved hypothetical protein, likely COG2 (ANID8226.1), respectively. To study the role of these proteins in the COG complex, an AlcA promoter replacement strategy was performed. When grown on AlcA-suppressive media, the AlcA-promoter COG4 and AlcApromoter COG7 strains displayed wild type growth at a restrictive temperature, while the AlcA-promoter COG1 and AlcA-promoter COG2 strains displayed swollen cells and abnormal polarity similar to that observed in the swoP1 mutant phenotype at a restrictive temperature. This data suggest that COG1 and COG2 are necessary for proper function of the COG complex in A. nidulans while COG4 and COG7 are not.
Full conference title:
- Asperfest 9 (2012)