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Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay
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The Ras and Rho GTPases genetically interact to co-ordinately regulate cell polarity during development in

Kylie J Boyce1, Michael J Hynes, Alex Andrianopoulos

  • 1Department of Genetics, University of Melbourne, Melbourne, Victoria, Australia 3010.

Molecular Microbiology
|February 22, 2005
PubMed

Insights

Ras and Rho GTPases regulate fungal development. RasA acts upstream of CflA (Cdc42) and CflB (Rac) to control cell polarization and morphogenesis in Penicillium marneffei.

Area of Science:

  • Molecular Biology
  • Mycology
  • Cell Biology

Background:

  • Ras and Rho GTPases are crucial for eukaryotic cell polarization and development.
  • Existing models from yeast and mammalian cells do not fully explain GTPase functions in all eukaryotes.
  • Filamentous fungi possess Rac-like proteins alongside Ras and Cdc42, suggesting unique regulatory roles.

Purpose of the Study:

  • To investigate the distinct functions of Ras and Rho GTPases in the dimorphic fungus Penicillium marneffei.
  • To understand how these GTPases interact to regulate fungal morphogenesis during growth and development.
  • To elucidate the specific roles of RasA, CflA (Cdc42), and CflB (Rac) in P. marneffei.

Main Methods:

  • Genetic analysis involving the generation of double mutants.
  • Study of Rho GTPases cflA and cflB, and the Ras GTPase rasA.
  • Phenotypic analysis of P. marneffei growth and development at different temperatures (25°C and 37°C).

Main Results:

  • RasA functions upstream of CflA (Cdc42) to regulate spore germination and polarized growth in both hyphal and yeast forms.
  • RasA also exhibits CflA-independent functions.
  • CflA (Cdc42) and CflB (Rac) cooperate to control hyphal cell polarization, with unique roles in conidial germination, yeast cell growth, conidiophore development, and hyphal branching.

Conclusions:

  • RasA, CflA (Cdc42), and CflB (Rac) play coordinated and distinct roles in regulating the morphogenesis of Penicillium marneffei.
  • The findings highlight the complex GTPase regulatory network governing fungal development.
  • This study provides insights into GTPase function in fungi, extending beyond yeast and mammalian paradigms.

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