5IIG: Structure Of The Spx-ttm Domain Fragment Of The Yeast Inorganic Polyphophate Polymerase Vtc4 (form A)

Citation:
Abstract
Phosphorus is a macronutrient taken up by cells as inorganic phosphate (P(i)). How cells sense cellular P(i) levels is poorly characterized. Here, we report that SPX domains--which are found in eukaryotic phosphate transporters, signaling proteins, and inorganic polyphosphate polymerases--provide a basic binding surface for inositol polyphosphate signaling molecules (InsPs), the concentrations of which change in response to P(i) availability. Substitutions of critical binding surface residues impair InsP binding in vitro, inorganic polyphosphate synthesis in yeast, and P(i) transport in Arabidopsis In plants, InsPs trigger the association of SPX proteins with transcription factors to regulate P(i) starvation responses. We propose that InsPs communicate cytosolic P(i) levels to SPX domains and enable them to interact with a multitude of proteins to regulate P(i) uptake, transport, and storage in fungi, plants, and animals.
PDB ID: 5IIGDownload
MMDB ID: 138612
PDB Deposition Date: 2016/3/1
Updated in MMDB: 2016/09
Experimental Method:
x-ray diffraction
Resolution: 2.99  Å
Source Organism:
Similar Structures:
Biological Unit for 5IIG: monomeric; determined by author and by software (PISA)
Molecular Components in 5IIG
Label Count Molecule
Protein (1 molecule)
1
Vacuolar Transporter Chaperone 4(Gene symbol: VTC4)
Molecule annotation
Chemicals (4 molecules)
1
4
* Click molecule labels to explore molecular sequence information.

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