Related Experiment Video

Updated: Jul 9, 2026

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans
07:32

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

Published on: March 19, 2015

Amt2 permease is required to induce ammonium-responsive invasive growth and mating in Cryptococcus neoformans

Julian C Rutherford1, Xiaorong Lin, Kirsten Nielsen

  • 1Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC 27710, USA.

Eukaryotic Cell
|December 7, 2007
PubMed

Insights

Cryptococcus neoformans ammonium permeases Amt1 and Amt2 are crucial for growth under nitrogen limitation. While not affecting virulence, Amt2 regulates invasive growth and mating in response to nutrient cues.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Mycology

Background:

  • The AmtB/Mep/Rh protein family facilitates ammonium transport across cell membranes in diverse organisms.
  • Specific fungal Amt proteins are essential for initiating filamentous growth.
  • Cryptococcus neoformans is a pathogenic basidiomycete with significant medical relevance.

Purpose of the Study:

  • To investigate the functions of two Amt proteins, Amt1 and Amt2, in Cryptococcus neoformans.
  • To determine the roles of these ammonium permeases in fungal growth, virulence, and mating.

Main Methods:

  • Gene knockout mutagenesis to create single (amt1, amt2) and double (amt1 amt2) mutants.
  • Phenotypic analysis of mutants under various nitrogen conditions.
  • Assessment of virulence in established cryptococcosis models.
  • Quantification of virulence factors (melanin, capsule) and invasive growth.

Main Results:

  • Amt1 and Amt2 function as low- and high-affinity ammonium permeases, respectively.
  • A double mutant lacking both permeases cannot grow under ammonium-limiting conditions.
  • AMT2 expression is induced by nitrogen limitation, while AMT1 is constitutive.
  • Mutants showed wild-type virulence, with no impairment in melanin or capsule formation.
  • Amt2 is essential for initiating haploid invasive growth and mating under low-nitrogen conditions.

Conclusions:

  • Amt1 and Amt2 are critical for ammonium uptake and growth in C. neoformans under nutrient-poor environments.
  • These permeases do not influence C. neoformans virulence factors like melanin or capsule.
  • Amt2 plays a key role in regulating invasive growth and mating, potentially acting as an ammonium sensor in signaling pathways responding to nutritional cues.

More Related Videos

Assay for Adhesion and Agar Invasion in S. cerevisiae04:36

Assay for Adhesion and Agar Invasion in S. cerevisiae

Published on: November 8, 2006

Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions10:56

Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions

Published on: June 22, 2019

Related Concept Videos

Yeast Signaling01:28

Yeast Signaling

Yeasts are single-celled organisms, but unlike bacteria, they are eukaryotes (cells with a nucleus). Cell signaling in yeast is similar to signaling in other eukaryotic cells. A ligand, such as a protein or a small molecule released from a yeast cell, attaches to a receptor on the cell surface. The binding stimulates second-messenger kinases to activate or inactivate transcription factors that further regulate gene expression. Many of the yeast intracellular signaling cascades have similar...
Cryptococcal Meningitis01:27

Cryptococcal Meningitis

Cryptococcal meningitis is a life-threatening opportunistic infection predominantly associated with HIV/AIDS, accounting for over 100,000 deaths annually worldwide. However, it also affects individuals with other forms of immunosuppression, including those undergoing immunosuppressive therapy, organ transplant recipients, patients with innate immunodeficiencies, and individuals with hematological disorders. The infection is caused mainly by Cryptococcus neoformans and Cryptococcus gattii,...
Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...