Distinct Substrate and Intermediate Recognition via Mutation Effects on Mycobacterium tuberculosis Methionyl-tRNA...

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Tuberculosis remains a global health crisis, with drug resistance necessitating novel therapeutic targets.
• Methionyl-tRNA synthetase (MetRS) in Mycobacterium tuberculosis (Mtb) is essential for protein synthesis and a promising drug target.

Purpose of the Study:

• To elucidate the structure-function relationships of Mtb MetRS.
• To understand the molecular basis of substrate recognition and the impact of mutations on enzyme activity.

Main Methods:

• Detailed sequence analyses of wild-type and mutant Mtb MetRS.
• Extensive molecular dynamics (MD) simulations (36 μs total) of Mtb MetRS in substrate-bound and intermediate states.
• Analysis of differential dynamics and binding effects.

Main Results:

• Wild-type Mtb MetRS substrate state is more stable than the intermediate state.
• Mutants exhibit decreased stability in the substrate state but increased stability in the intermediate state.
• Mutations disrupt substrate-protein interactions, affecting pyrophosphate-ATP exchange, while having minimal impact after intermediate formation.

Conclusions:

• The study reveals the distinct recognition mechanisms for substrate and intermediate states by Mtb MetRS.
• A clear molecular mechanism for activity loss in MetRS mutants has been established.
• Findings provide insights for developing new anti-tuberculosis drugs targeting MetRS.