Participation of Candida albicans transcription factor RLM1 in cell wall biogenesis and virulence

PLoS One. 2014 Jan 23;9(1):e86270. doi: 10.1371/journal.pone.0086270. eCollection 2014.

Abstract

Candida albicans cell wall is important for growth and interaction with the environment. RLM1 is one of the putative transcription factors involved in the cell wall integrity pathway, which plays an important role in the maintenance of the cell wall integrity. In this work we investigated the involvement of RLM1 in the cell wall biogenesis and in virulence. Newly constructed C. albicans Δ/Δrlm1 mutants showed typical cell wall weakening phenotypes, such as hypersensitivity to Congo Red, Calcofluor White, and caspofungin (phenotype reverted in the presence of sorbitol), confirming the involvement of RLM1 in the cell wall integrity. Additionally, the cell wall of C. albicans Δ/Δrlm1 showed a significant increase in chitin (213%) and reduction in mannans (60%), in comparison with the wild-type, results that are consistent with cell wall remodelling. Microarray analysis in the absence of any stress showed that deletion of RLM1 in C. albicans significantly down-regulated genes involved in carbohydrate catabolism such as DAK2, GLK4, NHT1 and TPS1, up-regulated genes involved in the utilization of alternative carbon sources, like AGP2, SOU1, SAP6, CIT1 or GAL4, and genes involved in cell adhesion like ECE1, ALS1, ALS3, HWP1 or RBT1. In agreement with the microarray results adhesion assays showed an increased amount of adhering cells and total biomass in the mutant strain, in comparison with the wild-type. C. albicans mutant Δ/Δrlm1 strain was also found to be less virulent than the wild-type and complemented strains in the murine model of disseminated candidiasis. Overall, we showed that in the absence of RLM1 the modifications in the cell wall composition alter yeast interaction with the environment, with consequences in adhesion ability and virulence. The gene expression findings suggest that this gene participates in the cell wall biogenesis, with the mutant rearranging its metabolic pathways to allow the use of alternative carbon sources.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Candida albicans / metabolism*
  • Candida albicans / pathogenicity
  • Candidemia / microbiology*
  • Cell Wall / metabolism*
  • Female
  • Fungal Proteins / physiology*
  • Gene Expression Regulation, Fungal
  • Kidney / microbiology
  • Kidney / pathology
  • Mice
  • Mice, Inbred BALB C
  • Transcription Factors / physiology*
  • Transcriptome
  • Virulence

Substances

  • Fungal Proteins
  • Transcription Factors

Grants and funding

This work was supported by CBMA (Centre of Molecular and Environmental Biology) through the FCT (Fundação para a Ciência e Tecnologia) project PEst-C/BIA/UI4050/2011. Yolanda Delgado-Silva was supported by an ALbAN scholarship (N° E07D400922PE), and Alexandra Correia by SFRH/BD/31354/2006 fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.