A Ras-like GTPase Is Involved in Hyphal Growth Guidance in the Filamentous Fungus Ashbya gossypiiV⃞

AUTOR(ES)

Bauer, Yasmina

FONTE

The American Society for Cell Biology

RESUMO

Characteristic features of morphogenesis in filamentous fungi are sustained polar growth at tips of hyphae and frequent initiation of novel growth sites (branches) along the extending hyphae. We have begun to study regulation of this process on the molecular level by using the model fungus Ashbya gossypii. We found that the A. gossypii Ras-like GTPase Rsr1p/Bud1p localizes to the tip region and that it is involved in apical polarization of the actin cytoskeleton, a determinant of growth direction. In the absence of RSR1/BUD1, hyphal growth was severely slowed down due to frequent phases of pausing of growth at the hyphal tip. During pausing events a hyphal tip marker, encoded by the polarisome component AgSPA2, disappeared from the tip as was shown by in vivo time-lapse fluorescence microscopy of green fluorescent protein-labeled AgSpa2p. Reoccurrence of AgSpa2p was required for the resumption of hyphal growth. In the Agrsr1/bud1Δ deletion mutant, resumption of growth occurred at the hyphal tip in a frequently uncoordinated manner to the previous axis of polarity. Additionally, hyphal filaments in the mutant developed aberrant branching sites by mislocalizing AgSpa2p thus distorting hyphal morphology. These results define AgRsr1p/Bud1p as a key regulator of hyphal growth guidance.

Documentos Relacionados

• Maximal Polar Growth Potential Depends on the Polarisome Component AgSpa2 in the Filamentous Fungus Ashbya gossypiiV⃞
• RIC, a calmodulin-binding Ras-like GTPase.
• The Ras-like GTPase Gem is involved in cell shape remodelling and interacts with the novel kinesin-like protein KIF9
• The ras-like yeast YPT1 gene is itself essential for growth, sporulation, and starvation response.
• Interaction cloning of Rabin3, a novel protein that associates with the Ras-like GTPase Rab3A.