Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:2.3.3.1 (
citrate synthase
)
4,488
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The peroxisomal biogenesis factor
Pex14p
is an essential component of the peroxisomal matrix protein import machinery. Together with Pex13p and Pex17p, it is part of the membrane-associated peroxisomal docking complex in yeast, facilitating the binding of cargo-loaded receptor proteins for translocation of cargo proteins into the peroxisome. Furthermore,
Pex14p
is part of peroxisomal import pores. The central role of
Pex14p
in peroxisomal matrix protein import processes renders it an obvious target for regulatory mechanisms such as protein phosphorylation. To explore this possibility, we examined the state of
Pex14p
phosphorylation in
Saccharomyces cerevisiae
. Phos-tag-SDS-PAGE of
Pex14p
affinity-purified from solubilized membranes revealed
Pex14p
as multi-phosphorylated protein. Using mass spectrometry, we identified 16 phosphorylation sites, with phosphorylation hot spots located in the N- and C-terminal regions of
Pex14p
. Analysis of phosphomimicking and non-phosphorylatable variants of
Pex14p
revealed a decreased import of GFP carrying a peroxisomal targeting signal type 1, indicating a functional relevance of
Pex14p
phosphorylation in peroxisomal matrix protein import. We show that this effect can be ascribed to the phosphomimicking mutation at serine 266 of
Pex14p
(
Pex14p
-S266D). We further screened the subcellular distribution of 23 native GFP-tagged peroxisomal matrix proteins by high-content fluorescence microscopy. Only Cit2p, the peroxisomal isoform of
citrate synthase
, was affected in the
Pex14p
-S266D mutant, showing increased cytosolic localization. Cit2p is part of the glyoxylate cycle, which is required for the production of essential carbohydrates when yeast is grown on non-fermentable carbon sources.
Pex14p
-S266 phosphosite mutants showed reversed growth phenotypes in oleic acid and ethanol with acetyl-CoA formed in peroxisomes and the cytosol, respectively. Overexpression of Cit2p rescued the growth phenotype of yeast cells expressing
Pex14p
-S266D in oleic acid. Our data indicate that phosphorylation of
Pex14p
at S266 provides a mechanism for controlling the peroxisomal import of Cit2p, which helps
S. cerevisiae
cells to adjust their carbohydrate metabolism according to the nutritional conditions.
...
PMID:Pex14p Phosphorylation Modulates Import of Citrate Synthase 2 Into Peroxisomes in
Saccharomyces cerevisiae
. 3304 91
