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Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans

Directional growth and tissue invasion by hyphae of the pathogenic fungus, Candida albicans, are disrupted by deletion of the small GTPase, Rsr1, which localizes Cdc42 and its kinase, Cla4, to the site of polarized growth. We investigated additional abnormalities observed in rsr1Δ hyphae, including...

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Autores principales: Bedekovic, T., Agnew, E., Brand, A. C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7554666/
https://www.ncbi.nlm.nih.gov/pubmed/33051364
http://dx.doi.org/10.1128/mBio.01666-20
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author Bedekovic, T.
Agnew, E.
Brand, A. C.
author_facet Bedekovic, T.
Agnew, E.
Brand, A. C.
author_sort Bedekovic, T.
collection PubMed
description Directional growth and tissue invasion by hyphae of the pathogenic fungus, Candida albicans, are disrupted by deletion of the small GTPase, Rsr1, which localizes Cdc42 and its kinase, Cla4, to the site of polarized growth. We investigated additional abnormalities observed in rsr1Δ hyphae, including vacuole development, cytoplasm inheritance, mitochondrial morphology, septin ring organization, nuclear division and migration, and branching frequency, which together demonstrate a fundamental role for Rsr1 in cellular organization. Rsr1 contains a C-terminal CCAAX box, which putatively undergoes both reversible palmitoylation and farnesylation for entry into the secretory pathway. We expressed variants of Rsr1 with mutated C244 or C245, or which lacked GTPase activity (Rsr1(K16N) and Rsr1(G12V)), in the rsr1Δ background and compared the resulting phenotypes with those of mutants lacking Bud5 (Rsr1 GEF), Bud2 (Rsr1 GAP), or Cla4. Bud5 was required only for cell size and bud site selection in yeast, suggesting there are alternative activators for Rsr1 in hyphae. Septin ring and vacuole dynamics were restored by expression of unpalmitoylated Rsr1(C244S), which localized to endomembranes, but not by cytoplasmic Rsr1(C245A) or GTP/GDP-locked Rsr1, suggesting Rsr1 functions at intracellular membranes in addition to the plasma membrane. Rsr1(K16N) or cytoplasmic Rsr1(C245A) restored normal nuclear division but not septin ring or vacuole dynamics. Rsr1-GDP therefore plays a specific role in suppressing START, which can be signaled from the cytosol. Via differential palmitoylation and activity states, Rsr1 operates at diverse cell sites to orchestrate proper nuclear division and inheritance during constitutive polarized growth. As cla4Δ phenocopied rsr1Δ, it is likely these functions involve Cdc42-Cla4 activity.
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spelling pubmed-75546662020-10-19 Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans Bedekovic, T. Agnew, E. Brand, A. C. mBio Research Article Directional growth and tissue invasion by hyphae of the pathogenic fungus, Candida albicans, are disrupted by deletion of the small GTPase, Rsr1, which localizes Cdc42 and its kinase, Cla4, to the site of polarized growth. We investigated additional abnormalities observed in rsr1Δ hyphae, including vacuole development, cytoplasm inheritance, mitochondrial morphology, septin ring organization, nuclear division and migration, and branching frequency, which together demonstrate a fundamental role for Rsr1 in cellular organization. Rsr1 contains a C-terminal CCAAX box, which putatively undergoes both reversible palmitoylation and farnesylation for entry into the secretory pathway. We expressed variants of Rsr1 with mutated C244 or C245, or which lacked GTPase activity (Rsr1(K16N) and Rsr1(G12V)), in the rsr1Δ background and compared the resulting phenotypes with those of mutants lacking Bud5 (Rsr1 GEF), Bud2 (Rsr1 GAP), or Cla4. Bud5 was required only for cell size and bud site selection in yeast, suggesting there are alternative activators for Rsr1 in hyphae. Septin ring and vacuole dynamics were restored by expression of unpalmitoylated Rsr1(C244S), which localized to endomembranes, but not by cytoplasmic Rsr1(C245A) or GTP/GDP-locked Rsr1, suggesting Rsr1 functions at intracellular membranes in addition to the plasma membrane. Rsr1(K16N) or cytoplasmic Rsr1(C245A) restored normal nuclear division but not septin ring or vacuole dynamics. Rsr1-GDP therefore plays a specific role in suppressing START, which can be signaled from the cytosol. Via differential palmitoylation and activity states, Rsr1 operates at diverse cell sites to orchestrate proper nuclear division and inheritance during constitutive polarized growth. As cla4Δ phenocopied rsr1Δ, it is likely these functions involve Cdc42-Cla4 activity. American Society for Microbiology 2020-10-13 /pmc/articles/PMC7554666/ /pubmed/33051364 http://dx.doi.org/10.1128/mBio.01666-20 Text en Copyright © 2020 Bedekovic et al. https://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Research Article
Bedekovic, T.
Agnew, E.
Brand, A. C.
Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
title Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
title_full Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
title_fullStr Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
title_full_unstemmed Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
title_short Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
title_sort rsr1 palmitoylation and gtpase activity status differentially coordinate nuclear, septin, and vacuole dynamics in candida albicans
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7554666/
https://www.ncbi.nlm.nih.gov/pubmed/33051364
http://dx.doi.org/10.1128/mBio.01666-20
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