3g3t
Crystal structure of a eukaryotic polyphosphate polymerase in complex with orthophosphate
Structural highlights
FunctionVTC4_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.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPolyphosphate (polyP) occurs ubiquitously in cells, but its functions are poorly understood and its synthesis has only been characterized in bacteria. Using x-ray crystallography, we identified a eukaryotic polyphosphate polymerase within the membrane-integral vacuolar transporter chaperone (VTC) complex. A 2.6 angstrom crystal structure of the catalytic domain grown in the presence of adenosine triphosphate (ATP) reveals polyP winding through a tunnel-shaped pocket. Nucleotide- and phosphate-bound structures suggest that the enzyme functions by metal-assisted cleavage of the ATP gamma-phosphate, which is then in-line transferred to an acceptor phosphate to form polyP chains. Mutational analysis of the transmembrane domain indicates that VTC may integrate cytoplasmic polymer synthesis with polyP membrane translocation. Identification of the polyP-synthesizing enzyme opens the way to determine the functions of polyP in lower eukaryotes. Catalytic core of a membrane-associated eukaryotic polyphosphate polymerase.,Hothorn M, Neumann H, Lenherr ED, Wehner M, Rybin V, Hassa PO, Uttenweiler A, Reinhardt M, Schmidt A, Seiler J, Ladurner AG, Herrmann C, Scheffzek K, Mayer A Science. 2009 Apr 24;324(5926):513-6. PMID:19390046[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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