Function of homologs of yeast dynamins in the filamentous ascomycete Ashbya gossypii.
Ivan Schlatter, Peter Philippsen, Dominic Hoepfner
Applied Microbiology, Biozentrum, University Basel, Klingelbergstr. 50, Basel, 4056, Switzerland
The complete genome of Ashbya gossypii is sequenced and all genes are annotated. The close relationship to the model organism S. cerevisiae (95% of all A. gossypii genes have a homologue in S. cerevisiae ) and the availability of efficient tools for gene targeting make this fungus an ideal system to study biogenesis and long range transport of organelles. Dynamins are involved in the morphology of several organelles. Dynamins are large GTPases found in all eukaryotic cells and can self-assemble into rings or spirals. This leads to the hypothesis that dynamin wraps around the necks of budding vesicles or membranous compartments where it plays a key role in membrane fission. In S. cerevisiae dynamins are involved in morphogenesis of mitochondria and peroxisomes and in vesicle trafficking. We are interested whether dynamins fulfill similar roles in A. gossypii. In contrast to S. cerevisiae this fungus grows as network of long and branching hyphae without undergoing cell separation. First we deleted the four dynamin genes AgDNM1, AgMGM1, AgFZO1 and AgVPS1. Deletions of AgVPS1 and AgDNM1 are viable, but both deletion strains have decreased growth speeds and are no longer able to sporulate. Actin staining showed, that the Agvps1 Δ strain generates much thicker septa with many attached actin patches. In the Agdnm1 Δ strain septa looked normal but the mitochondria appeared partially collapsed and form long, thin continuous tubules instead of a net-like structure as in wild-type.