TY - JOUR
T1 - Homodimeric hexaprenyl pyrophosphate synthase from the thermoacidophilic crenarchaeon Sulfolobus solfataricus displays asymmetric subunit structures
AU - Sun, Han Yu
AU - Ko, Tzu Ping
AU - Kuo, Chih Jung
AU - Guo, Rey Ting
AU - Chou, Chia Cheng
AU - Liang, Po Huang
AU - Wang, Andrew H.J.
PY - 2005/12
Y1 - 2005/12
N2 - 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.
AB - 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.
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U2 - 10.1128/JB.187.23.8137-8148.2005
DO - 10.1128/JB.187.23.8137-8148.2005
M3 - Article
C2 - 16291686
AN - SCOPUS:28044459167
SN - 0021-9193
VL - 187
SP - 8137
EP - 8148
JO - Journal of Bacteriology
JF - Journal of Bacteriology
IS - 23
ER -