Poster abstracts

Poster number 146 submitted by Melissa Tosiano

Edc3p is not required for P-Body condensation, heat tolerance, or hyphal phenotype in diverse Candida albicans strains

Melissa A. Tosiano (Biological Sciences, Carnegie Mellon University), Frederick Lanni (Biological Sciences, Carnegie Mellon University), Gemma E. May (Biological Sciences, Carnegie Mellon University), C. Joel McManus (Biological Sciences, Carnegie Mellon University)

Abstract:
Localization of mRNA to ribonucleoprotein granules (RNPs) such as P-bodies (PBs) and stress granules (SGs) is crucial for translational repression as well as reprogramming the transcriptome during stress. RNPs have been extensively studied in S. cerevisiae. However, the extent to which these functions are conserved in other fungi remains opaque. The human fungal pathogen Candida albicans forms filamentous hyphae, which are strongly linked to virulence1. Prior work demonstrated that C. albicans forms SGs2 and PBs3 under acute stress in vitro. Additionally, PB scaffolding protein and enhancer of decapping Edc3p has been implicated in PB condensation, heat resistance, and filamentation in an auxotrophic C. albicans strain. This is contrary to the evidence in S. cerevisiae where PBs are highly redundant structures unaltered by the loss of multiple scaffolding proteins including Edc3p4.

To examine RNP formation during C. albicans filamentation, we fluorescently tagged and imaged canonical SG and PB markers. We found that both RNPs condensed in response to acute heat shock. Interestingly, SGs are not present during physiologically relevant filamentation conditions, while PBs are abundant. As in S. cerevisiae, prototrophic C. albicans SC5314 edc3 Δ/Δ retained PB formation in response to acute heat shock and 4-hours of physiologically relevant stress. Due to pronounced diversity in C. albicans strains, we generated EDC3 homozygous deletions in prototrophic strains representing five different clades. Surprisingly, we found that in all five strains the absence of Edc3p did not lead to temperature sensitivity or hyphal phenotype defects. In the future, we will investigate if the absence of PB activator of decapping Dhh1p impedes filamentation in prototrophic C. albicans as was documented in auxotrophic C. albicans and S. cerevisiae5.

References:
1.Thompson, DS., et al. 2011 Coevolution of morphology and virulence in Candida species. PMID:21764907
2.O’Meara, TR. et al. 2019 Global proteomic analyses define an environmentally contingent Hsp90 interactome and reveal chaperone-dependent regulation of stress granule proteins and the R2TP complex in a fungal pathogen. PMID:31283755
3.Jung, JH. & Kim, J. 2011 Accumulation of P-bodies in Candida albicans under different stress and filamentous growth conditions. PMID:22056521
4.Rao, BS. & Parker, R. 2017 Numerous interactions act redundantly to assemble a tunable size of P bodies in Saccharomyces cerevisiae. PMID:29078371
5.Shively, CA. et al. 2015 Large-scale analysis of kinase signaling in yeast pseudohyphal development identifies regulation of ribonucleoprotein granules. PMID:26447709

Keywords: P-Bodies, C albicans, post-transcriptional regulation