Structure, Biochemistry, and Inhibition of Essential 4′-Phosphopantetheinyl Transferases from Two Species of Mycobacteria

Abstract

4′-Phosphopantetheinyl transferases (PPTase) post-translationally modify carrier proteins with a phosphopantetheine moiety, an essential reaction in all three domains of life. In the bacterial genus Mycobacteria, the Sfp-type PPTase activates pathways necessary for the biosynthesis of cell wall components and small molecule virulence factors. We solved the X-ray crystal structures and biochemically characterized the Sfp-type PPTases from two of the most prevalent Mycobacterial pathogens, PptT of M. tuberculosis and MuPPT of M. ulcerans. Structural analyses reveal significant differences in cofactor binding and active site composition when compared to previously characterized Sfp-type PPTases. Functional analyses including the efficacy of Sfp-type PPTase-specific inhibitors also suggest that the Mycobacterial Sfp-type PPTases can serve as therapeutic targets against Mycobacterial infections.

Unpacking the Pathogen Box—An Open Source Tool for Fighting Neglected Tropical Disease

“…Mutation of the biochemical machinery responsible for mycobactin biosynthesis inhibits M. tuberculosis growth whilst preventing the establishment of infection . Inhibitors for several enzymes in the mycobactin biosynthetic pathway have been investigated; however, of these targets, MbtA, which catalyses the condensation reaction between salicylate and an aroyl acyl carrier protein via a salicyl‐AMP intermediate ( 387 ), has been the most extensively and successfully exploited and has no mammalian homologues. Ferreras et al.…”

Breaking a pathogen's iron will: Inhibiting siderophore production as an antimicrobial strategy

“…The TAMRA-CoA is attached to a carrier domain by a PPTase, causing an increase in fluorescence polarization (the tumbling rate is slowed, because probe becomes bound to protein) [34]. A limited screen was performed using the PPTase from M. tuberculosis to label a carrier domain of VibB for vibriobactin biosynthesis ( Vibrio cholera , causative agent of cholera) or a carrier domain of mycocerosic acid synthase from M. tuberculosis [35]. The most effective inhibitors were calmidazolium and sanguinarine with low micromolar IC 50 values (Figure 4D).…”

“…[33] D. The two most inhibitory compounds of the PPTase from M. tuberculosis are shown, determined when using the fluorescence polarization assay where the probe is the FRET acceptor in part A. [34, 35]…”

Synthesis and Pharmacokinetic Evaluation of Siderophore Biosynthesis Inhibitors for Mycobacterium tuberculosis

“…26 Inhibition of mycobactin biosynthesis has also been fruitful, and inhibitors of enzymes within the pathway have been described for MbtA, 25, 27, 28 MbtI, 29 MbtM, 30 and PptT. 31 …”