An NlpC/P60 protein catalyzes a key step in peptidoglycan recycling at the intersection of energy recovery, cell division and immune evasion in the intracellular pathogenChlamydia trachomatis

Abstract

The obligate intracellular Chlamydiaceae do not need to resist osmotic challenges and thus lost their cell wall in the course of evolution. Nevertheless, these pathogens maintain a rudimentary peptidoglycan machinery for cell division. They build a transient peptidoglycan ring, which is remodeled during the process of cell division and degraded afterwards. Uncontrolled degradation of peptidoglycan poses risks to the chlamydial cell, as essential building blocks might get lost or trigger host immune response upon release into the host cell. Here, we provide evidence that a primordial enzyme class prevents energy intensive de novo synthesis and uncontrolled release of immunogenic peptidoglycan subunits in Chlamydia trachomatis. Our data indicate that the homolog of a Bacillus NlpC/P60 protein is widely conserved among Chlamydiales. We show that the enzyme is tailored to hydrolyze peptidoglycan-derived peptides, does not interfere with peptidoglycan precursor biosynthesis, and is targeted by cysteine protease inhibitors in vitro and in cell culture. The peptidase plays a key role in the underexplored process of chlamydial peptidoglycan recycling. Our study suggests that chlamydiae orchestrate a closed-loop system of peptidoglycan ring biosynthesis, remodeling, and recycling to support cell division and maintain long-term residence inside the host. Operating at the intersection of energy recovery, cell division and immune evasion, the peptidoglycan recycling NlpC/P60 peptidase could be a promising target for the development of drugs that combine features of classical antibiotics and anti-virulence drugs.

FLI1 localization to the chlamydial inclusion involves multiple mechanisms

“…Notably, induction of knockdown in the E.V. control strain demonstrated a ~48% decrease in infectious progeny (uninduced 6.08x10 6 IFU/mL; induced 2.79x10 6 IFU/mL; Figure 3E), consistent with increased energy requirements likely associated with dCas12 expression (59). For the L2/ct226 KD strain, infectious progeny were reduced by 69% following knockdown (uninduced 1.87x10 7 IFU/mL; induced 4.14x10 6 IFU/mL; Figure 3E).…”

Targeted repression of DNA topoisomerase I by CRISPRi reveals a critical function for it in theChlamydia trachomatisdevelopmental cycle

“…In contrast, topA transcripts were increased approximately two-fold in strain L2/Nt at 24 h pi after adding aTC. The biological relevance of this increase is unknown but may relate to a slight delay in developmental cycle progression when overexpressing the dCas12 (27).…”