- Functional Characterization and Protein Engineering of a Triterpene 3-/6-/2′-O-Glycosyltransferase Reveal a Conserved Residue Critical for the Regiospecificity
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Engineering the function of triterpene glucosyltransferases (GTs) is challenging due to the large size of the sugar acceptors. In this work, we identified a multifunctional glycosyltransferase AmGT8 catalyzing triterpene 3-/6-/2′-O-glycosylation from the medicinal plant Astragalus membranaceus. To engineer its regiospecificity, a small mutant library was built based on semi-rational design. Variants A394F, A394D, and T131V were found to catalyze specific 6-O, 3-O, and 2′-O glycosylation, respectively. The origin of regioselectivity of AmGT8 and its A394F variant was studied by molecular dynamics and hydrogen deuterium exchange mass spectrometry. Residue 394 is highly conserved as A/G and is critical for the regiospecificity of the C- and O-GTs TcCGT1 and GuGT10/14. Finally, astragalosides III and IV were synthesized by mutants A394F, T131V and P192E. This work reports biocatalysts for saponin synthesis and gives new insights into protein engineering of regioselectivity in plant GTs.
- Bao, Yang-Oujie,Gao, Bai-Han,Li, Fu-Dong,Qiao, Xue,Shi, Xiao-Meng,Su, Hui-Fei,Wang, Hai-Dong,Ye, Min,Yi, Yang,Zhang, Meng
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supporting information
(2022/01/06)
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- Synthetic Access Toward Cycloastragenol Glycosides
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The first efficient synthetic approach toward four types of the cycloartane glycosides, the cycloastragenol 25-O; 3-O; 3,6-O-bis; and 3,25-O-bisglycoside, have been established, which featured the PPY-mediated, concentration-controlled acetylation and Au(I)-catalyzed Yu glycosylation. Through the synthetic investigation, the reactivity sequence of the four OHs in cycloastragenol was fixed for the first time and a detour strategy for the highly efficient removal of bulky pivaloyl protecting groups was discovered.
- Liu, Ting,Liao, Jin-Xi,Hu, Yang,Tu, Yuan-Hong,Sun, Jian-Song
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p. 4170 - 4178
(2017/04/27)
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- Triterpene glycosides from Tragacantha stipulosa and their genins. Structure of cyclostipuloside E
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The known compound trojanoside A(1) and a new cycloartane glycoside cyclostipuloside E (2) were isolated from the aerial parts of Tragacantha stipulosa Boriss. The structure of cyclostipuloside E was proposed as 24R-cycloartan-3β,6α,16β,24,25-pentaol6,16,25-tri-O-β-D- glucopyranoside3-O-β-D-xylopyranoside based on physicochemical data and chemical transformations.
- Kaipnazarov,Uteniyazov,Saatov
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- TRITERPENE GLYCOSIDES OF Astragalus AND THEIR GENINS. XV. CYCLOSIVERSIOSIDES B AND D FROM Astragalus basineri
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Two new glycosides have been isolated from the roots of the plant Astragalus basineri Trautv. - cyclosiversiosides B and D.It has been shown that cyclosiversioside B is cyclosiversigenin 3-O-(2',3'-di-O-acetyl-β-D-xylopyranoside)-6-O-β-D-glucopyranoside.Cyclosiversioside D is cyclosiversigenin 3-O-(2'-O-acetyl-β-D'-xylopyranoside)-6-O-β-D-glucopyranoside.
- Umarova, R. U.,Svechnikova, A. N.,Abdullaev, N. D.,Gorovich, M. B.,Abubakirov, N. K.
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p. 174 - 177
(2007/10/02)
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- TRITERPENE GLYCOSIDES OF Astragalus AND THEIR GENINS. XIII. THE STRUCTURE OF CYCLOSIVERSIOSIDE H - A TRIGLYCERIDE FROM Astragalus sieversianus
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A new triglycoside of the cycloartane series has been isolated from the roots of Astragalus sieversianus Pall.; it is cyclosieversigenin 6-O-β-D-glucopyranoside 3-O-2)-β-D-xylopyranoside>.
- Svechnikova, A. N.,Umarova, R. U.,Abdullaev, N. D.,Gorovits, M. B.,Gorovits, T. T.,Abubakirov, N. K.
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p. 432 - 434
(2007/10/02)
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