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Comparing the Affinity of GTPase-binding Proteins using Competition Assays

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Published on: October 8, 2015

Small GTPase Rac promotes hyphal formation and microconidiogenesis in Trichophyton rubrum.

Masaki Ishii¹, Shinya Ohata¹

¹Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, Nishi-Tokyo, Japan.

|May 5, 2025

Summary

Rac is crucial for Trichophyton rubrum morphogenesis, controlling hyphal growth and microconidia formation. Cysteine in skin inhibits Rac-mediated microconidia production, impacting fungal infection.

Keywords:

Cdc42 Rac Trichophyton rubrum cysteine dermatophytosis hypha microconidia morphology

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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

Area of Science:

Medical Mycology
Cell Biology
Molecular Biology

Background:

Trichophyton rubrum causes dermatophytosis, thriving via hyphal growth and microconidia formation.
Morphogenesis is vital for T. rubrum infection, but its molecular control is unclear.
Cdc24 (guanine nucleotide exchange factor) is known to regulate polarity and hyphal growth.

Purpose of the Study:

Investigate the roles of Rac and Cdc42 in T. rubrum morphogenesis.
Elucidate the molecular mechanisms of hyphal and microconidia formation.
Determine the impact of host factors like cysteine on fungal development.

Main Methods:

Genetic manipulation of T. rubrum strains (Δrac, Δrac/Pcdc42).
Assessment of cell polarity using the cell polarity index.
Quantification of microconidia formation with and without cysteine supplementation.

Main Results:

Rac deficiency minimally impacted hyphal formation, but combined with Cdc42 repression, it significantly disrupted cell polarity.
Rac deficiency inhibited microconidia formation, while Cdc42 repression did not.
Cysteine reduced microconidia in wild-type but not Δrac strains, suggesting Rac-mediated inhibition.

Conclusions:

Rac and Cdc42 have overlapping roles in hyphal morphogenesis.
Rac is a key regulator of T. rubrum hyphal development and microconidia formation.
Host cysteine inhibits Rac-mediated microconidia production, influencing dermatophytosis pathogenesis.