Substrate selectivity of squalene synthetase

Pr, Ortiz de Montellano; Js, Wei; Wa, Vinson; Castillo, Rafael; As, Boparai

doi:10.1021/bi00631a015

Cited by 21 publications

(5 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CrtM was further engineered through mutations to accept C 25 farnesylgeranyl diphosphate, yielding C 40 , C 45 and C 50 homologues of dehydrosqualene in the presence of FPP, farnesylgeranyl diphosphate and GGPP 42 43 . In another study, SSs from yeast, pig and rat have been shown to accept non-natural derivatives of FPP, to generate several unnatural terpene products in vitro 45 46 . In addition, yeast SS has been shown to yield alternative products in vitro from FPP as a substrate under various non-physiological reaction conditions, such as in the absence of NADPH with extended incubation times or in the presence of an unreactive NADPH analogue 47 48 49 .…”

Section: Discussionmentioning

confidence: 99%

A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L

et al. 2016

View full text Add to dashboard Cite

The green microalga Botryococcus braunii is considered a promising biofuel feedstock producer due to its prodigious accumulation of hydrocarbon oils that can be converted into fuels. B. braunii Race L produces the C40 tetraterpenoid hydrocarbon lycopadiene via an uncharacterized biosynthetic pathway. Structural similarities suggest this pathway follows a biosynthetic mechanism analogous to that of C30 squalene. Confirming this hypothesis, the current study identifies C20 geranylgeranyl diphosphate (GGPP) as a precursor for lycopaoctaene biosynthesis, the first committed intermediate in the production of lycopadiene. Two squalene synthase (SS)-like complementary DNAs are identified in race L with one encoding a true SS and the other encoding an enzyme with lycopaoctaene synthase (LOS) activity. Interestingly, LOS uses alternative C15 and C20 prenyl diphosphate substrates to produce combinatorial hybrid hydrocarbons, but almost exclusively uses GGPP in vivo. This discovery highlights how SS enzyme diversification results in the production of specialized tetraterpenoid oils in race L of B. braunii.

show abstract

Section: Discussionmentioning

confidence: 99%

A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The filtrate was concentrated to a volume of 3 mL and purified by MPLC on SP207SS gel (2.5 x 25 cm column), eluting with water followed by a gradient created by the gradual addition of 2-propanol to a reservoir of water. Product fractions were combined and concentrated, and the aqueous solution was lyophilized to give 302 mg (50%) of 7 as a white solid: IR (KBr) 2926, 1653, 1507, 1150, 1026, 926, 878 cm"1; NMR (D20) 6 7.73 (d, 2H, «7=8.1 Hz,), 7.68 (d, 2H, J = 6.8 Hz), 7.56 (t, 2H, «7 = 7.5 Hz), 7.48 (d, 2H, «7 = 8.1 Hz), 7.46 (t, 1H, «7 = 7.3 Hz), 2.75 (m, 2H), 1.93 (m, 4H), 1.68 (m, 1H), 1.40 (d, 3H, J = 13.7 Hz); 13C NMR 20) ó 143.32,140.58, 137.98, 129.47, 129.27, 127.60, 126.99, 126.91, 43.68 (dd, «7 = 83, 116 Hz), 35.59, 32.96 (t, «7 = 5.9 Hz), 26.59, 16.97 (d, «7 = 92 Hz); MS (FAB, + ions) m/z 391 ( + 2H -Na), 413 ( + H), 435 (M + Na), 457 ( -H + 2Na). Anal.…”

Section: Methodsmentioning

confidence: 99%

1,1-Bisphosphonate Squalene Synthase Inhibitors: Interplay Between the Isoprenoid Subunit and the Diphosphate Surrogate

Magnin

Dickson²,

Logan³

et al. 1995

J. Med. Chem.

View full text Add to dashboard Cite

Inhibitors of squalene synthase have the potential to be superior cholesterol-lowering agents. We previously disclosed that lipophilic 1,1-bisphosphonates I are potent squalene synthase inhibitors and orally active cholesterol-lowering agents in animal models (Ciosek, C. P., Jr.; et al. J. Biol. Chem. 1993, 268, 24832-24837). In this paper, we describe modifications to the bisphosphonate moiety, in an attempt to reduce the number of acidic functions contained in these inhibitors. Replacing one of the acidic groups with a methyl (II, R2 = CH3) results in potent inhibitors when paired with a close mimic of the naturally occurring farnesyl moiety (R1 = farnesylethyl) but not when paired with the shorter isoprene surrogates (R1 = geranylethyl or 4-biphenylpropyl). In contrast, all three corresponding bisphosphonates I are potent squalene synthase inhibitors. Inhibitory potency is recovered with the shorter isoprene surrogates when R2 is CH2OH or CH2OCH3. It is proposed that these R2 groups serve as hydrogen bond acceptors with the active site of the enzyme. The properties of these compounds as cholesterol biosynthesis inhibitors in rats are described, and synthetic routes to these and related compounds are detailed.

show abstract

“…In the second half-reaction, thought to occur at a second catalytic site within the enzyme active center (6 -8), PSQPP undergoes heterolysis, isomerization, and reduction with NADPH to form squalene. It has been postulated that the SQS catalytic machinery consists of two nonidentical FPP binding sites (9,10), one that binds FPP in a conformation that facilitates its cleavage to yield an allylic carbocation, and one that binds FPP in an orientation that facilitates carbocation insertion into its C2-C3 double bond * The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C.…”

mentioning

confidence: 99%

Crystal Structure of Human Squalene Synthase

Pandit¹,

Danley²,

Schulte³

et al. 2000

Journal of Biological Chemistry

216

135

View full text Add to dashboard Cite

Squalene synthase catalyzes the biosynthesis of squalene, a key cholesterol precursor, through a reductive dimerization of two farnesyl diphosphate (FPP) molecules. The reaction is unique when compared with those of other FPP-utilizing enzymes and proceeds in two distinct steps, both of which involve the formation of carbocationic reaction intermediates. Because FPP is located at the final branch point in the isoprenoid biosynthesis pathway, its conversion to squalene through the action of squalene synthase represents the first committed step in the formation of cholesterol, making it an attractive target for therapeutic intervention. We have determined, for the first time, the crystal structures of recombinant human squalene synthase complexed with several different inhibitors. The structure shows that SQS is folded as a single domain, with a large channel in the middle of one face. The active sites of the two half-reactions catalyzed by the enzyme are located in the central channel, which is lined on both sides by conserved aspartate and arginine residues, which are known from mutagenesis experiments to be involved in FPP binding. One end of this channel is exposed to solvent, whereas the other end leads to a completely enclosed pocket surrounded by conserved hydrophobic residues. These observations, along with mutagenesis data identifying residues that affect substrate binding and activity, suggest that two molecules of FPP bind at one end of the channel, where the active center of the first half-reaction is located, and then the stable reaction intermediate moves into the deep pocket, where it is sequestered from solvent and the second half-reaction occurs. Five ␣ helices surrounding the active center are structurally homologous to the active core in the three other isoprenoid biosynthetic enzymes whose crystal structures are known, even though there is no detectable sequence homology.The isoprenoid biosynthetic pathway yields a structurally diverse family of low molecular weight molecules with a variety of physiological functions (1-3). In humans, the pathway produces such critical end-products as cholesterol, bile acids, dolichol, ubiquinone, steroid hormones, and prenylated proteins. Chain length-selective prenyltransferases catalyze the successive head-to-tail addition of the 5-carbon (C5-) isopentenyl diphosphate to the growing isoprene chain to form a series of linear C10-, C15-, C20-and C25-isoprenoid diphosphates. Cyclic terpenes are formed from these linear isoprenoid diphosphates through the actions of numerous class I terpene cyclases (3). The longer 30-carbon linear terpene, squalene, of cholesterol biosynthesis and the 40-carbon linear terpene, phytoene, of carotenoid biosynthesis are formed by head-to-head condensations, respectively, of two 15-carbon and 20-carbon isoprenoid diphosphates, through the actions of the prenyltransferases squalene synthase and phytoene synthase (4) and are subsequently converted into their respective cyclic terpenes through the action of specific class II terpene c...

show abstract

Substrate selectivity of squalene synthetase

Cited by 21 publications

References 29 publications

A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L

A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L

1,1-Bisphosphonate Squalene Synthase Inhibitors: Interplay Between the Isoprenoid Subunit and the Diphosphate Surrogate

Crystal Structure of Human Squalene Synthase

Contact Info

Product

Resources

About