In vivo virulence of Mycobacterium tuberculosis depends on a single homologue of the LytR-CpsA-Psr proteins

Abstract

LytR-cpsA-Psr (LCP) domain containing proteins fulfil important functions in bacterial cell wall synthesis. In Mycobacterium tuberculosis complex (Mtbc) strains, the causative agents of tuberculosis (TB), the genes Rv3484 and Rv3267 encode for LCP proteins which are putatively involved in arabinogalactan transfer to peptidoglycan. To evaluate the significance of Rv3484 for Mtbc virulence, we generated a deletion mutant in the Mtbc strain H37Rv and studied its survival in mice upon aerosol infection. The deletion mutant failed to establish infection demonstrating that Rv3484 is essential for growth in mice. Following an initial phase of marginal replication in the lungs until day 21, the Rv3484 deletion mutant was almost eliminated by day 180 post-infectionem. Interestingly, the mutant also showed higher levels of resistance to meropenem/clavulanate and lysozyme, both targeting peptidoglycan structure. We conclude that Rv3484 is essential for Mtbc virulence in vivo where its loss of function cannot be compensated by Rv3267.

Mycobacterium tuberculosis Rv2700 Contributes to Cell Envelope Integrity and Virulence

“…The M. tuberculosis genome encodes three LCP-LytR_C proteins, Rv0822c, Rv3267 (CpsA1/Lcp1), and Rv3484 (CpsA/CpsA2), and two LytR_C-only proteins, Rv0431 (VirR) and Rv2700 (4,5,(8)(9)(10)(11) (Fig. 1B).…”

LytR-CpsA-Psr Glycopolymer Transferases: Essential Bricks in Gram-Positive Bacterial Cell Wall Assembly

“…Although no analytically detectable difference was observed, the Δ cpsA2 deletion mutant in the M. tuberculosis strain H37Rv showed a changed phenotype in an in vivo mouse model, where the mutant was not able to grow, survive and infect. Furthermore, this strain displayed increased resistance to meropenem/clavulanate and rifampicin, which could not be compensated by cpsA1 [ 157 ]. Meropenem belongs to the carbapenem class of β-lactam antibiotics being poor substrates for BlaC, a protein encoded in the genome of M. tuberculosis which hydrolyses β-lactam antibiotics [ 158 ].…”

“…Meropenem belongs to the carbapenem class of β-lactam antibiotics being poor substrates for BlaC, a protein encoded in the genome of M. tuberculosis which hydrolyses β-lactam antibiotics [ 158 ]. Rifampicin did not target the cell wall but the authors argued that the permeability had changed and, therefore, the drug did not efficiently get into the cytoplasm as supported by measuring ethidium bromide uptake and efflux [ 66 , 157 ]. However, Grzegorzewicz et al could not determine increased resistance against rifampicin.…”

“…However, Grzegorzewicz et al could not determine increased resistance against rifampicin. According to Malm et al, this could be due to differences in the experimental set-up or resulting from a secondary effect and not from cpsA2 deletion [ 65 , 157 ].…”

Host Cell Targets of Released Lipid and Secreted Protein Effectors of Mycobacterium tuberculosis

“…Overall, the end result is that a CpsA deletion mutant ends up in an MCV that fuses with lysosomes which results in decreased intracellular survival (Koster et al, 2017). The Mtb CpsA mutant is also attenuated in the mouse model (Koster et al, 2017;Malm et al, 2018) and deletion of the Mm homolog attenuated this pathogen in the zebrafish model (Wang et al, 2015b). The CpsA mutant induces increased ROS due to the activated NOX2 and it is thus likely that host cell apoptosis levels are also increased as this was shown before for several Mtb mutants that results in increased phagosomal ROS (Hinchey et al, 2007;Miller et al, 2010;Sun et al, 2013).…”