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Time-Resolved Fluorescence Anisotropy from Single Molecules for Characterizing Local Flexibility in Biomolecules
Published on: April 25, 2025
Conformational freedom in tight binding enzymatic transition-state analogues
Matthew W Motley1, Vern L Schramm, Steven D Schwartz
1Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States.
The Journal of Physical Chemistry. B
|July 31, 2013
Summary
Transition-state analogues targeting bacterial 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidases (MTANs) can limit pathogenicity. Enhanced protein dynamics in E. coli MTAN explain its higher affinity for inhibitors compared to V. cholerae MTAN.
Area of Science:
- Biochemistry
- Molecular Biology
- Drug Discovery
Background:
- Bacterial quorum-sensing pathways are crucial for pathogenicity.
- 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidases (MTANs) are key enzymes in these pathways.
- Transition-state analogues (TSAs) are potential antivirulence agents that avoid antibiotic resistance pressure.
Purpose of the Study:
- To investigate the molecular basis for differential inhibitor affinity between E. coli MTAN (EcMTAN) and V. cholerae MTAN (VcMTAN).
- To explore the role of protein dynamics in the binding of BuT-DADMe-Immucillin-A (BDIA), a TSA.
Main Methods:
- Molecular dynamics (MD) simulations were performed on EcMTAN and VcMTAN complexed with BDIA.
- Analysis of electrostatic and hydrophobic interactions between the enzymes and the inhibitor.
- Assessment of protein flexibility and conformational dynamics in the catalytic sites.
Main Results:
- Electrostatic and hydrophobic interactions with BDIA were similar for both EcMTAN and VcMTAN.
- EcMTAN exhibited greater flexibility and conformational freedom in its catalytic site compared to VcMTAN.
- This increased flexibility in EcMTAN correlates with its significantly higher affinity for BDIA.
Conclusions:
- Protein dynamics, rather than static interactions, are critical for the differential affinity of MTANs to TSAs.
- Conserved motions related to the transition state in EcMTAN enhance BDIA binding.
- TSAs that accommodate protein motion during transition-state formation are superior inhibitors.
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