Overexpression of restores invasive filamentous growth and secretory vesicle clustering in a mutant.

Virulence of the human fungal pathogen depends on the switch from budding to filamentous growth. Deletion of the Arf GTPase Arl1 results in hyphae that are shorter as well as reduced virulence. How Arl1 is regulated during hyphal growth, a process characteristic of filamentous fungi, yet absent in , is unknown. Here, we investigated the importance of the Rab6 homolog, Ypt6, in Arl1-dependent hyphal growth and determined that overexpression specifically rescued the hyphal growth defect of an mutant, but not the converse. Furthermore, we show that deletion of results in an alteration of the distribution of the Rab8 homolog, Sec4, in hyphal cells and that this defect is restored upon overexpression.