The TOR Pathway Plays Pleiotropic Roles in Growth and Stress Responses of the Fungal Pathogen Cryptococcus neoformans

Yee Seul So, Dong Gi Lee, Alexander Idnurm, Giuseppe Ianiri, Yong Sun Bahn

Research output: Contribution to journalArticle

Abstract

The target of rapamycin (TOR) pathway is an evolutionarily conserved signal transduction system that governs a plethora of eukaryotic biological processes, but its role in Cryptococcus neoformans remains elusive. In this study, we investigated the TOR pathway by functionally characterizing two Tor-like kinases, Tor1 and Tlk1, in C. neoformans. We successfully deleted TLK1, but not TOR1. TLK1 deletion did not result in any evident in vitro phenotypes, suggesting that Tlk1 is dispensable for the growth of C. neoformans. We demonstrated that Tor1, but not Tlk1, is essential and the target of rapamycin by constructing and analyzing conditionally regulated strains and sporulation analysis of heterozygous mutants in the diploid strain background. To further analyze the Tor1 function, we constructed constitutive TOR1 overexpression strains. Tor1 negatively regulated thermotolerance and the DNA damage response, which are two important virulence factors of C. neoformans. TOR1 overexpression reduced Mpk1 phosphorylation, which is required for cell wall integrity and thermoresistance, and Rad53 phosphorylation, which governs the DNA damage response pathway. Tor1 is localized to the cytoplasm, but enriched in the vacuole membrane. Phosphoproteomics and transcriptomics revealed that Tor1 regulates a variety of biological processes, including metabolic processes, cytoskeleton organization, ribosome biogenesis, and stress response. TOR inhibition by rapamycin caused actin depolarization in a Tor1-dependent manner. Finally, screening rapamycin-sensitive and -resistant kinase and transcription factor mutants revealed that the TOR pathway may crosstalk with a number of stress signaling pathways. In conclusion, our study demonstrates that a single Tor1 kinase plays pleiotropic roles in C. neoformans.

Original languageEnglish
Pages (from-to)1241-1258
Number of pages18
JournalGenetics
Volume212
Issue number4
DOIs
Publication statusPublished - 2019 Jan 1

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Cryptococcus neoformans
Sirolimus
Growth
Biological Phenomena
Phosphotransferases
DNA Damage
Phosphorylation
Virulence Factors
Vacuoles
Cytoskeleton
Diploidy
Ribosomes
Cell Wall
Actins
Signal Transduction
Cytoplasm
Transcription Factors
Phenotype
Membranes

All Science Journal Classification (ASJC) codes

  • Genetics

Cite this

So, Yee Seul ; Lee, Dong Gi ; Idnurm, Alexander ; Ianiri, Giuseppe ; Bahn, Yong Sun. / The TOR Pathway Plays Pleiotropic Roles in Growth and Stress Responses of the Fungal Pathogen Cryptococcus neoformans. In: Genetics. 2019 ; Vol. 212, No. 4. pp. 1241-1258.
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The TOR Pathway Plays Pleiotropic Roles in Growth and Stress Responses of the Fungal Pathogen Cryptococcus neoformans. / So, Yee Seul; Lee, Dong Gi; Idnurm, Alexander; Ianiri, Giuseppe; Bahn, Yong Sun.

In: Genetics, Vol. 212, No. 4, 01.01.2019, p. 1241-1258.

Research output: Contribution to journalArticle

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