ReferenceID 3608

Quorum sensing controls hyphal initiation in Candida albicans through Ubr1-mediated protein degradation

Proc Natl Acad Sci U S A

Candida albicans is the most common cause of invasive fungal infections in humans. Its ability to undergo the morphological transition from yeast to hyphal growth forms is critical for its pathogenesis. Hyphal initiatio

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Reference Id
3608
Evidence Id
20198
Core Evidence Id
20198
Source Reference Id
518
Herb2 Reference Id
HBREF000868
Subject Paper Key
HBIN026385_24449897
Pubmed Id
24449897
Doi
10.1073/pnas.1318690111
Paper Title
Quorum sensing controls hyphal initiation in Candida albicans through Ubr1-mediated protein degradation
Paper Abstract
Candida albicans is the most common cause of invasive fungal infections in humans. Its ability to undergo the morphological transition from yeast to hyphal growth forms is critical for its pathogenesis. Hyphal initiation requires the activation of the cAMP-PKA pathway, which down-regulates the expression of NRG1, the major repressor of hyphal development. Hyphal initiation also requires inoculation of a small amount of C. albicans cells from overnight culture to fresh medium. This inoculation releases the inhibition from farnesol, a quorum-sensing molecule of C. albicans, that accumulated in the spent medium. Here, we show that farnesol inhibits hyphal initiation mainly through blocking the protein degradation of Nrg1. Through screening a kinase mutant library, we identified Sok1 as the kinase required for Nrg1 degradation during inoculation. SOK1 expression is transiently activated on inoculation during hyphal initiation, and overexpression of SOK1 overcomes the farnesol-mediated inhibition of hyphal initiation. Screening a collection of transcription factor mutants, the homeodomain-containing transcription repressor Cup9 is found to be responsible for the repression of SOK1 expression in response to farnesol inhibition. Interestingly, farnesol inhibits Cup9 degradation mediated by the N-end rule E3 ubiquitin ligase, Ubr1. Therefore, hyphal initiation requires both the cAMP-PKA pathway-dependent transcriptional down-regulation of NRG1 and Sok1-mediated degradation of Nrg1 protein. The latter is triggered by the release from farnesol inhibition of Cup9 degradation and consequently, derepression of SOK1 transcription. Neither pathway alone is sufficient for hyphal initiation.
Journal
Proc Natl Acad Sci U S A
Publish Year
2014
Experiment Subject
c. albicans cells
Experiment Type
Cell Experiment
Phenotype Related
Paper Title Cn
Paper Title En
Quorum sensing controls hyphal initiation in Candida albicans through Ubr1-mediated protein degradation
Bilingual Status
semi_complete