Kinetic, thermodynamic, and structural properties of the aminoglycoside
Emtricitabine (FTC) and lamivudine (3TC), containing an oxathiolane ring with unnatural (−)-stereochemistry, are widely used nucleoside reverse transcriptase inhibitors (NRTIs) in anti-HIV therapy. Treatment with FTC or 3TC primarily selects for the HIV-1 RT M184V/I resistance mutations. Here we provide a comprehensive kinetic and structural basis for inhibiting HIV-1 RT by (−)-FTC-TP and (−)-3TC-TP and drug resistance by M184V. (−)-FTC-TP and (−)-3TC-TP have higher binding affinities (1/
- Award ID(s):
- 1856617
- NSF-PAR ID:
- 10154174
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Biology
- Volume:
- 2
- Issue:
- 1
- ISSN:
- 2399-3642
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT N3‐ acetyltransferase‐VIa (AAC‐VIa) are determined. Among the aminoglycosideN3 ‐acetyltransferases, AAC‐VIa has one of the most limited substrate profiles. Kinetic studies showed that only five aminoglycosides are substrates for this enzyme with a range of fourfold difference ink catvalues. Larger differences inK M(∼40‐fold) resulted in ∼30‐fold variation ink cat/K M. Binding of aminoglycosides to AAC‐VIa was enthalpically favored and entropically disfavored with a net result of favorable Gibbs energy (ΔG < 0). A net deprotonation of the enzyme, ligand, or both accompanied the formation of binary and ternary complexes. This is opposite of what was observed with several other aminoglycosideN3 ‐acetyltransferases, where ligand binding causes more protonation. The change in heat capacity (ΔCp) was different in H2O and D2O for the binary enzyme–sisomicin complex but remained the same in both solvents for the ternary enzyme–CoASH–sisomicin complex. Unlike, most other aminoglycoside‐modifying enzymes, the values of ΔCp were within the expected range of protein‐carbohydrate interactions. Solution behavior of AAC‐VIa was also different from the more promiscuous aminoglycosideN3 ‐acetyltransferases and showed a monomer‐dimer equilibrium as detected by analytical ultracentrifugation (AUC). Binding of ligands shifted the enzyme to monomeric state. Data also showed that polar interactions were the most dominant factor in dimer formation. Overall, thermodynamics of ligand‐protein interactions and differences in protein behavior in solution provide few clues on the limited substrate profile of this enzyme despite its >55% sequence similarity to the highly promiscuous aminoglycosideN3 ‐acetyltransferase. Proteins 2017; 85:1258–1265. © 2017 Wiley Periodicals, Inc. -
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Abstract Recently, we reported the discovery of a novel endoglucanase of the glycoside hydrolase family 12 (GH12), designated IfCelS12A, from the haloalkaliphilic anaerobic bacterium
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IfCelS12A from an anaerobic alkaliphile Iocasia fronsfrigidae shows salt tolerance •
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