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Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion

The homotypic fusion of yeast vacuoles requires the Rab-family GTPase Ypt7p and its effector complex, homotypic fusion and vacuole protein sorting complex (HOPS). Although the vacuolar kinase Yck3p is required for the sensitivity of vacuole fusion to proteins that regulate the Rab GTPase cycle—Gdi1p...

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Autores principales: Zick, Michael, Wickner, William
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3431944/
https://www.ncbi.nlm.nih.gov/pubmed/22787280
http://dx.doi.org/10.1091/mbc.E12-04-0279
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author Zick, Michael
Wickner, William
author_facet Zick, Michael
Wickner, William
author_sort Zick, Michael
collection PubMed
description The homotypic fusion of yeast vacuoles requires the Rab-family GTPase Ypt7p and its effector complex, homotypic fusion and vacuole protein sorting complex (HOPS). Although the vacuolar kinase Yck3p is required for the sensitivity of vacuole fusion to proteins that regulate the Rab GTPase cycle—Gdi1p (GDP-dissociation inhibitor [GDI]) or Gyp1p/Gyp7p (GTPase-activating protein)—this kinase phosphorylates HOPS rather than Ypt7p. We addressed this puzzle in reconstituted proteoliposome fusion reactions with all-purified components. In the presence of HOPS and Sec17p/Sec18p, there is comparable fusion of 4-SNARE (soluble N-ethylmaleimide–sensitive factor attachment protein receptor) proteoliposomes when they have Ypt7p bearing either GDP or GTP, a striking exception to the rule that only GTP-bound forms of Ras-superfamily GTPases have active conformations. However, the phosphorylation of HOPS by recombinant Yck3p confers a strict requirement for GTP-bound Ypt7p for binding phosphorylated HOPS, for optimal membrane tethering, and for proteoliposome fusion. Added GTPase-activating protein promotes GTP hydrolysis by Ypt7p, and added GDI captures Ypt7p in its GDP-bound state during nucleotide cycling. In either case, the net conversion of Ypt7:GTP to Ypt7:GDP has no effect on HOPS binding or activity but blocks fusion mediated by phosphorylated HOPS. Thus guanine nucleotide specificity of the vacuolar fusion Rab Ypt7p is conferred through downstream posttranslational modification of its effector complex.
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spelling pubmed-34319442012-11-16 Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion Zick, Michael Wickner, William Mol Biol Cell Articles The homotypic fusion of yeast vacuoles requires the Rab-family GTPase Ypt7p and its effector complex, homotypic fusion and vacuole protein sorting complex (HOPS). Although the vacuolar kinase Yck3p is required for the sensitivity of vacuole fusion to proteins that regulate the Rab GTPase cycle—Gdi1p (GDP-dissociation inhibitor [GDI]) or Gyp1p/Gyp7p (GTPase-activating protein)—this kinase phosphorylates HOPS rather than Ypt7p. We addressed this puzzle in reconstituted proteoliposome fusion reactions with all-purified components. In the presence of HOPS and Sec17p/Sec18p, there is comparable fusion of 4-SNARE (soluble N-ethylmaleimide–sensitive factor attachment protein receptor) proteoliposomes when they have Ypt7p bearing either GDP or GTP, a striking exception to the rule that only GTP-bound forms of Ras-superfamily GTPases have active conformations. However, the phosphorylation of HOPS by recombinant Yck3p confers a strict requirement for GTP-bound Ypt7p for binding phosphorylated HOPS, for optimal membrane tethering, and for proteoliposome fusion. Added GTPase-activating protein promotes GTP hydrolysis by Ypt7p, and added GDI captures Ypt7p in its GDP-bound state during nucleotide cycling. In either case, the net conversion of Ypt7:GTP to Ypt7:GDP has no effect on HOPS binding or activity but blocks fusion mediated by phosphorylated HOPS. Thus guanine nucleotide specificity of the vacuolar fusion Rab Ypt7p is conferred through downstream posttranslational modification of its effector complex. The American Society for Cell Biology 2012-09-01 /pmc/articles/PMC3431944/ /pubmed/22787280 http://dx.doi.org/10.1091/mbc.E12-04-0279 Text en © 2012 Zick and Wickner. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0). “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society of Cell BD; are registered trademarks of The American Society of Cell Biology.
spellingShingle Articles
Zick, Michael
Wickner, William
Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion
title Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion
title_full Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion
title_fullStr Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion
title_full_unstemmed Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion
title_short Phosphorylation of the effector complex HOPS by the vacuolar kinase Yck3p confers Rab nucleotide specificity for vacuole docking and fusion
title_sort phosphorylation of the effector complex hops by the vacuolar kinase yck3p confers rab nucleotide specificity for vacuole docking and fusion
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3431944/
https://www.ncbi.nlm.nih.gov/pubmed/22787280
http://dx.doi.org/10.1091/mbc.E12-04-0279
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