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

Han Yu Sun, Tzu Ping Ko, Chih Jung Kuo, Rey Ting Guo, Chia Cheng Chou, Po Huang Liang, Andrew H.J. Wang

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

Hexaprenyl pyrophosphate synthase (HexPPs) from Sulfolobus solfataricus catalyzes the synthesis of trans-C30-hexaprenyl pyrophosphate (HexPP) by reacting two isopentenyl pyrophosphate molecules with one geranylgeranyl pyrophosphate. The crystal structure of the homodimeric C30-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 (αI, αJ, αK, and part of αH) 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 π-π stacking interactions of aromatic side chains found in FPPs and OPPs. Finally, the three-conformer switched model may explain the catalytic process for HexPPs.

Original languageEnglish
Pages (from-to)8137-8148
Number of pages12
JournalJournal of Bacteriology
Volume187
Issue number23
DOIs
Publication statusPublished - Dec 2005
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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