title: Catalytic core of a membrane-associated eukaryotic polyphosphate polymerase.
abstract: Polyphosphate (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.
authors.affiliation: European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hothorn
authors.forename: Heinz
authors.initials: H
authors.lastname: Neumann
authors.forename: Esther D
authors.initials: ED
authors.lastname: Lenherr
authors.forename: Mark
authors.initials: M
authors.lastname: Wehner
authors.forename: Vladimir
authors.initials: V
authors.lastname: Rybin
authors.forename: Paul O
authors.initials: PO
authors.lastname: Hassa
authors.forename: Andreas
authors.initials: A
authors.lastname: Uttenweiler
authors.forename: Monique
authors.initials: M
authors.lastname: Reinhardt
authors.forename: Andrea
authors.initials: A
authors.lastname: Schmidt
authors.forename: Jeanette
authors.initials: J
authors.lastname: Seiler
authors.forename: Andreas G
authors.initials: AG
authors.lastname: Ladurner
authors.forename: Christian
authors.initials: C
authors.lastname: Herrmann
authors.forename: Klaus
authors.initials: K
authors.lastname: Scheffzek
authors.forename: Andreas
authors.initials: A
authors.lastname: Mayer
mesh_terms: D001692:Biological Transport; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010770:Phosphotransferases / Q000737:chemistry* / Q000378:metabolism; D011122:Polyphosphates / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D011122:Polyphosphates; D029701:Saccharomyces cerevisiae Proteins; D010770:Phosphotransferases