Identification and characterization of zincophores in Mycobacterium avium ssp. paratuberculosis, including their translocation pathway and impact on virulence

Paratuberculosis - Johne’s disease - is a worldwide occurring, progressive, fatal enteritis of ruminants caused by Mycobacterium avium ssp. paratuberculosis (MAP). The primary host tissue harboring MAP is the distal ileum, which is also the main site of zinc absorption of the host. MAP is equipped with a canonical ZnuABC zinc uptake transporter, which is also found in other mycobacterial pathogens, and two additional unique zinc uptake transporters located on the MAP-specific large sequence polymorphisms LSP14 and LSP15. Moreover, LSP14 harbors a putative zincophore gene cluster - sid - not found in other closely related or pathogenic mycobacteria, suggesting the presence of an additional zinc support system in MAP. We previously showed that this cluster is regulated zinc dependently by the Zinc uptake regulator Zur and encodes an NRPS (Non Ribosomal Peptide Synthetase), which is thought to synthesize a zincophore. In preliminary experiments, we detected for the first time a MAP zincophore candidate using metal isotope-coded profiling (MICP). Given the essential role of zinc and zincophores in bacterial survival and establishment of infection, it is of great importance to elucidate and fully understand the function of these systems in MAP zinc homeostasis and pathogenicity. The project aims to further identify, confirm and characterize MAP zincophores, to link the sid cluster to zincophore production, to elucidate of the role of sid in MAP zinc homeostasis and intracellular survival, and to investigate zincophore translocation systems. Our expected findings will contribute to the understanding of zinc homeostasis in MAP and other mycobacteria.

PhD start: 10/01/2025