A Fluorogenic Trehalose Probe for Tracking Phagocytosed Mycobacterium tuberculosis

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Abstract
Tuberculosis (TB) disease is a global epidemic caused by the pathogenic Mycobacterium tuberculosis (Mtb). Tools that can track the replication status of viable Mtb cells within macrophages are vital for the elucidation of host-pathogen interactions. Here, we present a cephalosphorinase-dependent green trehalose (CDG-Tre) fluorogenic probe that enables fluorescence labeling of single live Bacille Calmette-Guérin (BCG) cells within macrophages at concentrations as low as 2 µM. CDG-Tre fluoresces upon activation by BlaC, the β-lactamase uniquely expressed by Mtb, and the fluorescent product is subsequently incorporated within the bacterial cell wall via trehalose metabolic pathway. CDG-Tre showed high selectivity for mycobacteria over other clinically prevalent species in the Corynebacterineae suborder. The unique labeling strategy of BCG by CDG-Tre provides a versatile tool for tracking Mtb in both pre- and post-phagocytosis and elucidating fundamental physiological and pathological processes related to the mycomembrane.
Funding Information
  • National Institute of Allergy and Infectious Diseases (R01AI125286)
  • Center for Molecular Analysis and Design, Stanford University