Intercepting a Mycobacterial Biosynthetic Pathway with Covalent Labeling

Area of Science:

• Microbiology
• Chemical Biology
• Biochemistry

Background:

• The mycobacterial cell envelope is vital for infection and protection, but its glycan components are difficult to modify.
• Existing labeling methods have limitations in probe delivery and effectiveness.

Purpose of the Study:

• To develop a new, effective strategy for labeling mycobacterial cell envelopes.
• To create a small molecule probe that exploits enzyme-substrate relationships for targeted modification.

Main Methods:

• Synthesized an azide-substituted trans-β-lactone probe (AzLac).
• Utilized a probegenic approach where enzyme activity reveals probe functionality.
• Incorporated AzLac into mycobacterial cell envelope glycans using mycolyltransferases.
• Investigated probe targeting using Corynebacterium glutamicum deletion strains.

Main Results:

• AzLac selectively labels the inner leaflet of the mycomembrane in mycobacteria, including Mycobacterium tuberculosis.
• Cmt2 was identified as a primary mycolyltransferase target for AzLac.
• Demonstrated AzLac's utility in attaching DNA barcodes to mycobacteria for infection tracking.

Conclusions:

• The AzLac probe offers a valuable tool for monitoring and tracking the mycobacterial cell envelope.
• The probegenic strategy of masking and revealing recognition motifs has broad applicability for diverse cellular targets.