Selective inhibition of Mycobacterium tuberculosis GpsI unveils a novel strategy to target the RNA metabolism

Area of Science:

• Molecular Biology
• Microbiology
• Drug Discovery

Background:

• Polyribonucleotide nucleotidyl-transferases (PNPases) are crucial for mRNA degradation.
• Mycobacterial PNPase, GpsI, is essential in Mycobacterium tuberculosis (Mtb) and involved in RNA processing.
• GpsI represents an underexplored target for anti-tubercular drug development.

Purpose of the Study:

• To identify and validate GpsI as a novel drug target in Mtb.
• To characterize a specific inhibitor (X1) of Mtb-GpsI.
• To elucidate the mechanism of action and specificity of the inhibitor.

Main Methods:

• Whole-cell screening to identify potential inhibitors.
• Biochemical assays to confirm GpsI inhibition by X1.
• Engineering of GpsI variants and use of recombinant Mycobacterium smegmatis.
• Cryo-electron microscopy to determine the drug-binding site.

Main Results:

• GpsI was confirmed as a viable drug target in Mtb.
• The inhibitor X1 selectively inhibits Mtb-GpsI activity.
• Amino acids 328 and 527 of GpsI were identified as critical for X1's selective activity.
• Cryo-EM revealed the GpsI-X1-poly(A) complex structure, detailing the drug-binding pocket.

Conclusions:

• Mtb-GpsI is a promising and underexplored target for novel anti-tubercular agents.
• The inhibitor X1 demonstrates potent and selective inhibition of Mtb-GpsI.
• Structural and biochemical data provide a molecular basis for X1's specificity, guiding future drug design.