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Crystal structure for the mutant W136E of Sulfolobus solfataricus hexaprenyl pyrophosphate synthaseCrystal structure for the mutant W136E of Sulfolobus solfataricus hexaprenyl pyrophosphate synthase
Structural highlights
FunctionHEXPP_SACS2 Catalyzes consecutive E-type condensation of two isopentenyl pyrophosphate (IPP) molecules with an allylic substrate such as geranylgeranyl diphosphate (GGPP), farnesyl diphosphate (FPP) or geranyl diphosphate (GPP) to yield the medium-chain product trans-C30-hexaprenyl pyrophosphate (HexPP). GGPP is the physiological substrate.[1] [2] Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHexaprenyl 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. Homodimeric hexaprenyl pyrophosphate synthase from the thermoacidophilic crenarchaeon Sulfolobus solfataricus displays asymmetric subunit structures.,Sun HY, Ko TP, Kuo CJ, Guo RT, Chou CC, Liang PH, Wang AH J Bacteriol. 2005 Dec;187(23):8137-48. PMID:16291686[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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