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Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans

Publication ,  Journal Article
Waugh, MS; Nichols, CB; DeCesare, CM; Cox, GM; Heitman, J; Alspaugh, JA
Published in: Microbiology
2002

The Ras1 signal transduction pathway controls the ability of the pathogenic fungus Cryptococcus neoformans to grow at high temperatures and to mate. A second RAS gene was identified in this organism. RAS2 is expressed at a very low level compared to RAS1, and a ras2 mutation caused no alterations in vegetative growth rate, differentiation or virulence factor expression. The ras2 mutant strain was equally virulent to the wild-type strain in the murine inhalational model of cryptococcosis. Although a ras1 ras2 double mutant strain is viable, mutation of both RAS genes results in a decreased growth rate at all temperatures compared to strains with either single mutation. Overexpression of the RAS2 gene completely suppressed the ras1 mutant mating defect and partially suppressed its high temperature growth defect. After prolonged incubation at a restrictive temperature, the ras1 mutant demonstrated actin polarity defects that were also partially suppressed by RAS2 overexpression. These studies indicate that the C. neoformans Ras1 and Ras2 proteins share overlapping functions, but also play distinct signalling roles. Our findings also suggest a mechanism by which Ras1 controls growth of this pathogenic fungus at 37 °C, supporting a conserved role for Ras homologues in microbial cellular differentiation, morphogenesis and virulence.

Duke Scholars

Published In

Microbiology

Publication Date

2002

Volume

148

Issue

1

Start / End Page

191 / 201

Related Subject Headings

  • Microbiology
 

Citation

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MLA
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Waugh, M. S., Nichols, C. B., DeCesare, C. M., Cox, G. M., Heitman, J., & Alspaugh, J. A. (2002). Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans. Microbiology, 148(1), 191–201.
Waugh, M. S., C. B. Nichols, C. M. DeCesare, G. M. Cox, J. Heitman, and J. A. Alspaugh. “Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans.” Microbiology 148, no. 1 (2002): 191–201.
Waugh MS, Nichols CB, DeCesare CM, Cox GM, Heitman J, Alspaugh JA. Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans. Microbiology. 2002;148(1):191–201.
Waugh, M. S., et al. “Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans.” Microbiology, vol. 148, no. 1, 2002, pp. 191–201.
Waugh MS, Nichols CB, DeCesare CM, Cox GM, Heitman J, Alspaugh JA. Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans. Microbiology. 2002;148(1):191–201.

Published In

Microbiology

Publication Date

2002

Volume

148

Issue

1

Start / End Page

191 / 201

Related Subject Headings

  • Microbiology