Simvastatin Synthase

Function

Simvastatin synthase or transesterase (LovD) is a 46 kDa acyltransferase found in the lovastatin biosynthetic pathway and catalyzes the final step of Lovastatin biosynthesis^[1]. Pictured here is the generated double mutant C40A/C60N (G0), from wild type LovD (Figure 1).This enzyme is isolated from the natural product biosynthetic pathways of Aspergillus terreus, specifically the polyketide biosynthetic pathway. Simvastatin Synthase converts the inactive monacolin J acid (MJA) by dimethylbutyryl chloride to yield the protected form of simvastatin (Figure 2), which subsequently undergoes lactonization to yield Simvastatin^[2].

LovD can also synthesize the blockbuster drug simvastatin using MJA and a synthetic α-dimethylbutyryl thioester^[3].

Exploring the structure

LovD is a 413-amino acid protein predicted to have an α/β hydrolase fold based on primary sequence analysis^[4]. LovD has of two domains. The , which consists of residues 1–92 and 204–413, is a central seven-stranded antiparallel β-sheet flanked by α-helices on either face^[3]. The is smaller, consists of residues 93–203 and is primarily α-helical^[3].

At the core of the enzyme, there are notable loops peripheral to the active site, both in size and architecture. Upon ligand binding LovD undergoes a conformational change analogous to the closing of a catcher's mitt by these loops. This ringshaped ridge over the active site with fingers is composed of : residues 114–125, 147–173, 243–258, 321–327, and 388–391^[3].

LovD has at the following positions: C40, C49, C60, C72, C89, C216, C266, C380, and C395^[5].

Additional Information

As simvastatin is an active pharmaceutical ingredient in the cholesterol-lowering drug Zocor®, its efficient synthesis from lovastatin, via LovD is intensely pursued ^[1].

The protein-protein interaction between LovD and the acyl carrier protein domain of LovF facilitates the highly efficient tailoring reaction during LVA biosynthesis ^[1]. The α-S-methylbutyrate side chain is synthesized by the lovastatin diketide synthase (LDKS) LovF and then transferred by LovD regioselectively to the C8 hydroxyl of ^[5].

Among enzymes that of known structures, (cephalosporin esterase), is homologous to LovD: 26% sequence identity ^[6].

3D structures of simvastatin synthase

Updated on 13-August-2024

3hl9, 3hlb, 3hlc, 4lcl, 4lcm – AtLovD (mutant) – Aspergillus terreus

3hld, 3hle – AtLovD (mutant) + monacolin J acid

3hlf – AtLovD (mutant) + simvastatin

3hlg – AtLovD (mutant) + lovastatin

References

1. ↑ ^{1.0 1.1 1.2} Xie X, Watanabe K, Wojcicki WA, Wang CC, Tang Y. Biosynthesis of lovastatin analogs with a broadly specific acyltransferase. Chem Biol. 2006 Nov;13(11):1161-9. PMID:17113998 doi:10.1016/j.chembiol.2006.09.008
2. ↑ Gao X, Xie X, Pashkov I, Sawaya MR, Laidman J, Zhang W, Cacho R, Yeates TO, Tang Y. Directed evolution and structural characterization of a simvastatin synthase. Chem Biol. 2009 Oct 30;16(10):1064-74. PMID:19875080 doi:10.1016/j.chembiol.2009.09.017
3. ↑ ^{3.0 3.1 3.2 3.3} Xie X, Tang Y. Efficient synthesis of simvastatin by use of whole-cell biocatalysis. Appl Environ Microbiol. 2007 Apr;73(7):2054-60. Epub 2007 Feb 2. PMID:17277201 doi:10.1128/AEM.02820-06
4. ↑ Kennedy J, Auclair K, Kendrew SG, Park C, Vederas JC, Hutchinson CR. Modulation of polyketide synthase activity by accessory proteins during lovastatin biosynthesis. Science. 1999 May 21;284(5418):1368-72. PMID:10334994
5. ↑ ^{5.0 5.1} Xie X, Pashkov I, Gao X, Guerrero JL, Yeates TO, Tang Y. Rational improvement of simvastatin synthase solubility in Escherichia coli leads to higher whole-cell biocatalytic activity. Biotechnol Bioeng. 2009 Jan 1;102(1):20-8. PMID:18988191 doi:10.1002/bit.22028
6. ↑ Wagner UG, Petersen EI, Schwab H, Kratky C. EstB from Burkholderia gladioli: a novel esterase with a beta-lactamase fold reveals steric factors to discriminate between esterolytic and beta-lactam cleaving activity. Protein Sci. 2002 Mar;11(3):467-78. PMID:11847270