Mycobacterium abscessus virulence traits unraveled by transcriptomic profiling in amoeba and macrophages

Abstract

Free-living amoebae are thought to represent an environmental niche in which amoeba-resistant bacteria may evolve towards pathogenicity. To get more insights into factors playing a role for adaptation to intracellular life, we characterized the transcriptomic activities of the emerging pathogen Mycobacterium abscessus in amoeba and murine macrophages (Mϕ) and compared them with the intra-amoebal transcriptome of the closely related, but less pathogenic Mycobacterium chelonae. Data on up-regulated genes in amoeba point to proteins that allow M. abscessus to resist environmental stress and induce defense mechanisms, as well as showing a switch from carbohydrate carbon sources to fatty acid metabolism. For eleven of the most upregulated genes in amoeba and/or Mϕ, we generated individual gene knock-out M. abscessus mutant strains, from which ten were found to be attenuated in amoeba and/or Mϕ in subsequence virulence analyses. Moreover, transfer of two of these genes into the genome of M. chelonae increased the intra-Mϕ survival of the recombinant strain. One knock-out mutant that had the gene encoding Eis N-acetyl transferase protein (MAB_4532c) deleted, was particularly strongly attenuated in Mϕ. Taken together, M. abscessus intra-amoeba and intra-Mϕ transcriptomes revealed the capacity of M. abscessus to adapt to an intracellular lifestyle, with amoeba largely contributing to the enhancement of M. abscessus intra-Mϕ survival.

Structural analysis of the N‐acetyltransferase Eis1 from Mycobacterium abscessus reveals the molecular determinants of its incapacity to modify aminoglycosides

“…Solving the high-resolution structure of Eis2 Mab proved that this protein accommodates amikacin in its active site where the drug undergoes acetylation as supported in enzymatic assays 18 . Importantly, the deletion of eis2 Mab increases the susceptibility of M. abscessus to aminoglycosides, thus supporting our findings 17 modestly impacted the capacity of the mutant strain to infect macrophages and failed to modify the susceptibility to aminoglycosides as compared to an eis2 Mab mutant 19 . This suggests that Eis1 Mab and Eis2 Mab share very limited overlapping functions 17,19 .…”

Acanthamoeba castellanii as a Screening Tool for Mycobacterium avium Subspecies paratuberculosis Virulence Factors with Relevance in Macrophage Infection

“…Eukaryotic organisms like amoeba have long been noted to interact with mycobacterial species in the environment and, therefore, are part of the mycobacterial evolution [ 29 ]. It has been also demonstrated that intra-amoeba growth can increase bacterial virulence, and some common mechanisms have been implicated with the pathogen’s survival in amoebae as well as in macrophages [ 19 , 30 ]. For example, Mycobacterium avium subsp.…”

Non-Tuberculous Mycobacteria: Molecular and Physiological Bases of Virulence and Adaptation to Ecological Niches

“…For M. abscessus , the ESX-4 type VII secretion system has been implicated in resistance to amoeba phagocytosis, with mutants in esx-4 genes exhibiting a reduction in intra-amoeba replication [ 165 ]. Furthermore, a study analyzing the transcriptomic profile of M. abcessus in amoeba revealed a group of 45 up-regulated genes that allow mycobacteria to resist environmental stress and induce defense mechanisms [ 166 ].…”