Allosteric cooperation in β-lactam binding to a non-classical transpeptidase

Area of Science:

• Microbiology and Infectious Diseases
• Structural Biology
• Drug Discovery

Background:

• L,D-transpeptidases are crucial for peptidoglycan synthesis in Mycobacterium tuberculosis.
• Previous research identified only the catalytic site of L,D-transpeptidases, limiting understanding of their activity and inhibition.
• Understanding L,D-transpeptidase mechanisms is key to developing new anti-tuberculosis therapies.

Purpose of the Study:

• To elucidate the complete mechanism of L,D-transpeptidase activity and inhibition by beta-lactams.
• To identify novel binding sites on L,D-transpeptidases beyond the known catalytic site.
• To explore new avenues for structure-based drug design against Mycobacterium tuberculosis.

Main Methods:

• Identification of a novel allosteric site (S-pocket) on L,D-transpeptidase.
• Characterization of the S-pocket's binding to the sugar moiety of peptidoglycan substrates.
• Investigation of dual beta-lactam binding to the enzyme using structural and biochemical approaches.

Main Results:

• An allosteric S-pocket, 21 Å from the catalytic site, was identified, binding the sugar moiety of peptidoglycan.
• A second beta-lactam molecule was found to bind non-covalently to the S-pocket.
• Evidence supports cooperative binding of two beta-lactam molecules: one at the S-pocket and one covalently at the catalytic site.

Conclusions:

• A novel dual beta-lactam binding mechanism for L,D-transpeptidase in Mycobacterium tuberculosis has been uncovered.
• The identified allosteric site and cooperative binding offer new targets for drug development.
• This discovery paves the way for innovative structure-based drug design strategies against tuberculosis.