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Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans
08:24

Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans

Published on: February 27, 2018

Cryptococcus neoformans requires the ESCRT protein Vps23 for iron acquisition from heme, for capsule formation, and

Guanggan Hu1, Mélissa Caza, Brigitte Cadieux

  • 1Michael Smith Laboratories, Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC, Canada.

Infection and Immunity
|November 8, 2012
PubMed

Insights

Cryptococcus neoformans iron uptake and capsule formation are regulated by Vps23, an endosomal sorting complex required for transport (ESCRT) protein. This discovery links iron acquisition and virulence in fungal meningitis.

Area of Science:

  • Mycology
  • Molecular Biology
  • Pathogenesis

Background:

  • Iron availability critically influences Cryptococcus neoformans virulence, particularly in HIV/AIDS patients.
  • Mechanisms of iron sensing and uptake in human fungal pathogens remain poorly understood.

Purpose of the Study:

  • To investigate the role of iron acquisition mechanisms in Cryptococcus neoformans.
  • To identify genes involved in iron sensing and uptake, focusing on heme utilization.

Main Methods:

  • Agrobacterium-mediated T-DNA insertion mutagenesis of C. neoformans.
  • Screening for mutants with impaired growth on heme as the sole iron source.
  • Analysis of Vps23 gene function in iron uptake and capsule elaboration.

Main Results:

  • Mutants with insertions in the Vps23 gene exhibited growth defects on heme, suggesting impaired iron uptake.
  • Vps23 mutants showed defects in capsular polysaccharide elaboration, a key virulence factor.
  • Vps23 overexpression led to enlarged capsules and altered virulence in a mouse model.

Conclusions:

  • The endosomal sorting complex required for transport (ESCRT) protein Vps23 plays a crucial role in heme iron uptake and capsule formation in C. neoformans.
  • Vps23 function is essential for regulating the connection between iron availability and virulence factor deployment.

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