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Structure of SPX domain of the yeast inorganic polyphophate polymerase Vtc4 crystallized by carrier-driven crystallization in fusion with the macro domain of human histone macroH2A1.1
Structural highlights
FunctionH2AY_HUMAN Variant histone H2A which replaces conventional H2A in a subset of nucleosomes where it represses transcription. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Involved in stable X chromosome inactivation. Inhibits the binding of transcription factors and interferes with the activity of remodeling SWI/SNF complexes. Inhibits histone acetylation by EP300 and recruits class I HDACs, which induces a hypoacetylated state of chromatin. In addition, isoform 1, but not isoform 2, binds ADP-ribose and O-acetyl-ADP-ribose, and may be involved in ADP-ribose-mediated chromatin modulation.[1] [2] [3] [4] [5] VTC4_YEAST Component of the vacuolar transporter chaperone (VTC) complex, which plays a role in vacuolar membrane fusion. Required for SEC18/NSF activity in SNARE priming, membrane binding of LMA1 and V(0) trans-complex formation.[6] [7] [8] Publication Abstract from PubMedPhosphorus is a macronutrient taken up by cells as inorganic phosphate (Pi). How cells sense cellular Pilevels 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), whose concentrations change in response to Piavailability. Substitutions of critical binding surface residues impair InsP binding in vitro, inorganic polyphosphate synthesis in yeast and Pitransport inArabidopsis In plants, InsPs trigger the association of SPX proteins with transcription factors to regulate Pistarvation responses. We propose that InsPs communicate cytosolic Pilevels to SPX domains and enable them to interact with a multitude of proteins to regulate Piuptake, transport and storage in fungi, plants and animals. Control of eukaryotic phosphate homeostasis by inositol polyphosphate sensor domains.,Wild R, Gerasimaite R, Jung JY, Truffault V, Pavlovic I, Schmidt A, Saiardi A, Jessen HJ, Poirier Y, Hothorn M, Mayer A Science. 2016 Apr 14. pii: aad9858. PMID:27080106[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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