The vesicular transport protein Cgp1p/Vps54p/Tcs3p/Luv1p is required for the integrity of the actin cytoskeleton

Abstract.

The CGP1 gene was identified in a screen for mutations that were synthetic lethal in combination with a deletion of the gene (CPF1) for centromere and promoter factor 1. Cells deleted for CGP1 showed reduced viability, were temperature sensitive for growth and exhibited altered sensitivity to microtubule-destabilizing drugs. Furthermore, Δ cgp1 cells showed increased rates of loss of a circular minichromosome and defects in the positioning of the short mitotic spindle. Further phenotypic analysis of Δ cgp1 cells revealed that loss of Cgp1p function led to severe depolarization of the actin cytoskeleton. In addition, cells deleted for CGP1 were hypersensitive to the actin-disrupting compound Latrunculin-A, exhibited strongly reduced polarized localization of the unconventional myosin Myo2p, and showed defects in other actin-related processes, such as shmoo formation and cell wall integrity. Cgp1p was recently identified by several groups as Vps54p, which is a member of the VFT complex that is involved in vesicular protein transport at the level of the late Golgi, acting as a tethering factor. Our data show for the first time that Cgp1p/Vps54p links aspects of vesicular protein transport with the organization of the actin cytoskeleton.