Structures of Staphylococcus aureus D-tagatose-6-phosphate kinase implicate domain motions in specificity and mechanism

J Biol Chem. 2007 Jul 6;282(27):19948-57. doi: 10.1074/jbc.M701480200. Epub 2007 Apr 25.

Abstract

High resolution structures of Staphylococcus aureus d-tagatose-6-phosphate kinase (LacC) in two crystal forms are herein reported. The structures define LacC in apoform, in binary complexes with ADP or the co-factor analogue AMP-PNP, and in a ternary complex with AMP-PNP and D-tagatose-6-phosphate. The tertiary structure of the LacC monomer, which is closely related to other members of the pfkB subfamily of carbohydrate kinases, is composed of a large alpha/beta core domain and a smaller, largely beta "lid." Four extended polypeptide segments connect these two domains. Dimerization of LacC occurs via interactions between lid domains, which come together to form a beta-clasp structure. Residues from both subunits contribute to substrate binding. LacC adopts a closed structure required for phosphoryl transfer only when both substrate and co-factor are bound. A reaction mechanism similar to that used by other phosphoryl transferases is proposed, although unusually, when both substrate and co-factor are bound to the enzyme two Mg(2+) ions are observed in the active site. A new motif of amino acid sequence conservation common to the pfkB subfamily of carbohydrate kinases is identified.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / analogs & derivatives
  • Adenosine Diphosphate / chemistry*
  • Amino Acid Motifs
  • Bacterial Proteins / chemistry*
  • Binding Sites
  • Coenzymes / chemistry*
  • Magnesium / chemistry*
  • Phosphotransferases (Alcohol Group Acceptor) / chemistry*
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Staphylococcus aureus / enzymology*

Substances

  • Bacterial Proteins
  • Coenzymes
  • Adenosine Diphosphate
  • Phosphotransferases (Alcohol Group Acceptor)
  • tagatose 6-phosphate kinase
  • Magnesium

Associated data

  • PDB/2JG1
  • PDB/2JGV