Dynamin in fission and fusion

The same GTPase that tears membranes apart is needed to put them back together, based on results from Christopher Peters, Andreas Mayer, and colleagues (Université de Lausanne, Switzerland). The dual regulation may ensure that only one of the two competing processes goes on at any one time.

The Swiss group finds that yeast cells lacking the dynamin homologue Vps1p resemble both fission and fusion mutants. The effects were seen in the morphology of the vacuoles, where Vps1p was localized. Some cells had a single enlarged vacuole, whereas others had many small vacuolar fragments.

The two phenotypes were seen because Vps1p functions in both pathways. As expected given dynamin's known fission activity, vacuole fragmentation in response to salt stress was disrupted in the mutant. But vacuole fusion reactions also required Vps1p, which was found to...