Publications

• Change of product specificity of hexaprenyl diphosphate synthase from Sulfolobus solfataricus by introducing mimetic mutations.

  Hemmi H., Noike M., Nakayama T., Nishino T.

  The introduction of several sets of amino acid substitutions into the region around a substrate-binding site of a medium-chain (all-E) prenyl diphosphate synthase, hexaprenyl diphosphate synthase from a thermoacidophilic archaeon Sulfolobus solfataricus, to mimic the product determination mechanis ... >> More

  The introduction of several sets of amino acid substitutions into the region around a substrate-binding site of a medium-chain (all-E) prenyl diphosphate synthase, hexaprenyl diphosphate synthase from a thermoacidophilic archaeon Sulfolobus solfataricus, to mimic the product determination mechanisms of various kinds of short-chain enzymes revealed that the structure around the region of the medium-chain enzyme resembles those of eukaryotic farnesyl diphosphate synthases but not those of the other short-chain enzymes, reflecting the evolutional relationships among these enzymes. << Less

  Biochem Biophys Res Commun 297:1096-1101(2002) [PubMed] [EuropePMC]

• Homodimeric hexaprenyl pyrophosphate synthase from the thermoacidophilic crenarchaeon Sulfolobus solfataricus displays asymmetric subunit structures.

  Sun H.Y., Ko T.P., Kuo C.J., Guo R.T., Chou C.C., Liang P.H., Wang A.H.

  Hexaprenyl pyrophosphate synthase (HexPPs) from Sulfolobus solfataricus catalyzes the synthesis of trans-C(30)-hexaprenyl pyrophosphate (HexPP) by reacting two isopentenyl pyrophosphate molecules with one geranylgeranyl pyrophosphate. The crystal structure of the homodimeric C(30)-HexPPs resembles ... >> More

  Hexaprenyl pyrophosphate synthase (HexPPs) from Sulfolobus solfataricus catalyzes the synthesis of trans-C(30)-hexaprenyl pyrophosphate (HexPP) by reacting two isopentenyl pyrophosphate molecules with one geranylgeranyl pyrophosphate. The crystal structure of the homodimeric C(30)-HexPPs resembles those of other trans-prenyltransferases, including farnesyl pyrophosphate synthase (FPPs) and octaprenyl pyrophosphate synthase (OPPs). In both subunits, 10 core helices are arranged about a central active site cavity. Leu164 in the middle of the cavity controls the product chain length. Two protein conformers are observed in the S. solfataricus HexPPs structure, and the major difference between them occurs in the flexible region of residues 84 to 100. Several helices (alphaI, alphaJ, alphaK, and part of alphaH) and the associated loops have high-temperature factors in one monomer, which may be related to the domain motion that controls the entrance to the active site. Different side chain conformations of Trp136 in two HexPPs subunits result in weaker hydrophobic interactions at the dimer interface, in contrast to the symmetric pi-pi stacking interactions of aromatic side chains found in FPPs and OPPs. Finally, the three-conformer switched model may explain the catalytic process for HexPPs. << Less

  J. Bacteriol. 187:8137-8148(2005) [PubMed] [EuropePMC]

• Novel medium-chain prenyl diphosphate synthase from the thermoacidophilic archaeon Sulfolobus solfataricus.

  Hemmi H., Ikejiri S., Yamashita S., Nishino T.

  Two open reading frames which encode the homologues of (all-E) prenyl diphosphate synthase are found in the whole-genome sequence of Sulfolobus solfataricus, a thermoacidophilic archaeon. It has been suggested that one is a geranylgeranyl diphosphate synthase gene, but the specificity and biologic ... >> More

  Two open reading frames which encode the homologues of (all-E) prenyl diphosphate synthase are found in the whole-genome sequence of Sulfolobus solfataricus, a thermoacidophilic archaeon. It has been suggested that one is a geranylgeranyl diphosphate synthase gene, but the specificity and biological significance of the enzyme encoded by the other have remained unclear. Thus, we isolated the latter by the PCR method, expressed the enzyme in Escherichia coli cells, purified it, and characterized it. The archaeal enzyme, 281 amino acids long, is highly thermostable and requires Mg(2+) and Triton X-100 for full activity. It catalyzes consecutive E-type condensations of isopentenyl diphosphate with an allylic substrate such as geranylgeranyl diphosphate and yields the medium-chain product hexaprenyl diphosphate. Despite such product specificity, phylogenetic analysis revealed that the archaeal medium-chain prenyl diphosphate synthase is distantly related to the other medium- and long-chain enzymes but is closely related to eucaryal short-chain enzymes. << Less

  J. Bacteriol. 184:615-620(2002) [PubMed] [EuropePMC]