3aq0
From Proteopedia
Ligand-bound form of Arabidopsis medium/long-chain length prenyl pyrophosphate synthase (surface polar residue mutant)
Structural highlights
FunctionSPS3_ARATH May be involved in the supply of solanesyl diphosphate for ubiquinone-9 biosynthesis in mitochondria. Synthesizes C25 to C45 medium / long-chain products depending on the type of substrate available. Can use geranyl diphosphate, farnesyl diphosphate or geranylgeranyl diphosphate as substrates, but not dimethylallyl diphosphate.[1] [2] [3] [4] Publication Abstract from PubMedPrenyltransferases (PTSs) are involved in the biosynthesis of terpenes with diverse functions. Here a novel PTS from Arabidopsis thaliana as a trans-type polyprenyl pyrophosphate synthase (AtPPPS), which forms a trans double bond during each homoallylic substrate condensation, rather than a homomeric C(10)-geranyl pyrophosphate synthase as originally proposed. Biochemical and genetic complementation analyses indicate that AtPPPS synthesizes C(25) to C(45) medium/long-chain products. Its close relationship to other long-chain PTSs is also uncovered by phylogenetic analysis. A mutant of contiguous surface polar residues was produced by replacing four charged surface amino acids with alanines to facilitate the crystallization of the enzyme. The crystal structures of AtPPPS determined here in apo and ligand-bound forms further reveal an active-site cavity sufficient to accommodate the medium/long-chain products. The two monomers in each dimer adopt different conformations at the entrance of the active site depending on the binding of substrates. Taken together, these results suggest that AtPPPS is endowed with a unique functionality among the known PTSs. Structure and mechanism of an Arabidopsis medium/long-chain length prenyl pyrophosphate synthase.,Hsieh FL, Chang TH, Ko TP, Wang AH Plant Physiol. 2011 Jan 10. PMID:21220764[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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