Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity.
Details
State: Public
Version: author
Serval ID
serval:BIB_97FEDD1E48BE
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity.
Journal
Journal of Cell Science
ISSN
1477-9137 (Electronic)
ISSN-L
0021-9533
Publication state
Published
Issued date
2014
Volume
127
Number
23
Pages
5093-5104
Language
english
Abstract
Eukaryotes contain inorganic polyphosphate (polyP) and acidocalcisomes, which sequester polyP and store amino acids and divalent cations. Why polyP is sequestered in dedicated organelles is not known. We show that polyP produced in the cytosol of yeast becomes toxic. Reconstitution of polyP translocation with purified vacuoles, the acidocalcisomes of yeast, shows that cytosolic polyP cannot be imported, whereas polyP produced by the vacuolar transporter chaperone (VTC) complex, an endogenous vacuolar polyP polymerase, is efficiently imported and does not interfere with growth. PolyP synthesis and import require an electrochemical gradient, probably as a driving force for polyP translocation. VTC exposes its catalytic domain to the cytosol and carries nine vacuolar transmembrane domains. Mutations in the VTC transmembrane regions, which are likely to constitute the translocation channel, block not only polyP translocation but also synthesis. Given that they are far from the cytosolic catalytic domain of VTC, this suggests that the VTC complex obligatorily couples synthesis of polyP to its import in order to avoid toxic intermediates in the cytosol. Sequestration of otherwise toxic polyP might be one reason for the existence of acidocalcisomes in eukaryotes.
Keywords
Yeast vacuole, Inorganic polyphosphate, VTC complex, Acidocalcisome
Pubmed
Web of science
Open Access
Yes
Create date
02/01/2015 10:32
Last modification date
20/08/2019 15:59