Glycoside hydrolases (GH) are a large family of hydrolytic enzymes found in all domains of life. As such, they control a plethora of normal and pathogenic biological functions. Thus, understanding selective inhibition of GH enzymes at the atomic level can lead to the identification of new classes of therapeutics. In these studies, we identified a 4-⍺-glucoside of valienamine (8) as an inhibitor (IC50 of 484 ± 51 µM) of Streptomyces coelicolor (Sco) GlgE1-V279S which belongs to the GH13 Carbohydrate Active EnZyme (CAZy) family. The synthetic route to 8 and a closely related 4-⍺-glucoside of validamine (7) was achieved starting from readily available D-maltose. A key step in the synthesis was a chelation-controlled addition of vinylmagnesium bromide to a maltose-derived enone intermediate. X-ray structures of both 7 and 8 in complex with Sco GlgE1-V279S were solved to resolutions of 1.75 and 1.78 Å, respectively. Structural analysis revealed the valienamine derivative 8 binds the enzyme in an E2 conformation for the cyclohexene fragment. Also, the cyclohexene fragment shows a new hydrogen-bonding contact from the pseudo-diaxial C(3)-OH to the catalytic nucleophile Asp 394 at the enzyme active site. Asp 394, in fact, forms a bidentate interaction with both the C(3)-OH and C(7)-OH of the inhibitor. In contrast, compound 7 disrupts the catalytic sidechain interaction network of Sco GlgE1-V279S via steric interactions resulting in a conformation change in Asp 394. These findings will have implications for the design other aminocarbasugar-based GH13-inhibitors and will be useful for identifying more potent and selective inhibitors.
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No competing interests reported.
This is a list of supplementary files associated with this preprint. Click to download.
Retrosynthetic strategy to prepare 4-α-glycoside derivatives of valienamine and validamine from maltose.
Diastereoselective addition of vinylmagnesium bromide to enone 15.
Synthesis of diastereomers 27A and 27B from D-(+)-maltose (20)
RCM of dienes 27A and 27B.
Synthesis of 4-α-glycoside derivatives of validamine 7 and valienamine 8 from alkene 28A
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Posted 22 Mar, 2021
Received 04 Apr, 2021
Received 04 Apr, 2021
Received 04 Apr, 2021
Received 04 Apr, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
Invitations sent on 17 Mar, 2021
On 15 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
On 12 Mar, 2021
Posted 22 Mar, 2021
Received 04 Apr, 2021
Received 04 Apr, 2021
Received 04 Apr, 2021
Received 04 Apr, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
On 19 Mar, 2021
Invitations sent on 17 Mar, 2021
On 15 Mar, 2021
On 14 Mar, 2021
On 14 Mar, 2021
On 12 Mar, 2021
Glycoside hydrolases (GH) are a large family of hydrolytic enzymes found in all domains of life. As such, they control a plethora of normal and pathogenic biological functions. Thus, understanding selective inhibition of GH enzymes at the atomic level can lead to the identification of new classes of therapeutics. In these studies, we identified a 4-⍺-glucoside of valienamine (8) as an inhibitor (IC50 of 484 ± 51 µM) of Streptomyces coelicolor (Sco) GlgE1-V279S which belongs to the GH13 Carbohydrate Active EnZyme (CAZy) family. The synthetic route to 8 and a closely related 4-⍺-glucoside of validamine (7) was achieved starting from readily available D-maltose. A key step in the synthesis was a chelation-controlled addition of vinylmagnesium bromide to a maltose-derived enone intermediate. X-ray structures of both 7 and 8 in complex with Sco GlgE1-V279S were solved to resolutions of 1.75 and 1.78 Å, respectively. Structural analysis revealed the valienamine derivative 8 binds the enzyme in an E2 conformation for the cyclohexene fragment. Also, the cyclohexene fragment shows a new hydrogen-bonding contact from the pseudo-diaxial C(3)-OH to the catalytic nucleophile Asp 394 at the enzyme active site. Asp 394, in fact, forms a bidentate interaction with both the C(3)-OH and C(7)-OH of the inhibitor. In contrast, compound 7 disrupts the catalytic sidechain interaction network of Sco GlgE1-V279S via steric interactions resulting in a conformation change in Asp 394. These findings will have implications for the design other aminocarbasugar-based GH13-inhibitors and will be useful for identifying more potent and selective inhibitors.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
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