A 2-Pyridone-Amide Inhibitor Targets the Glucose Metabolism Pathway of Chlamydia trachomatis

Abstract

In a screen for compounds that inhibit infectivity of the obligate intracellular pathogen Chlamydia trachomatis, we identified the 2-pyridone amide KSK120. A fluorescent KSK120 analogue was synthesized and observed to be associated with the C. trachomatis surface, suggesting that its target is bacterial. We isolated KSK120-resistant strains and determined that several resistance mutations are in genes that affect the uptake and use of glucose-6-phosphate (G-6P). Consistent with an effect on G-6P metabolism, treatment with KSK120 blocked glycogen accumulation. Interestingly, KSK120 did not affect Escherichia coli or the host cell. Thus, 2-pyridone amides may represent a class of drugs that can specifically inhibit C. trachomatis infection.

Expansion of the Chlamydia trachomatis inclusion does not require bacterial replication

“…1A). This observed effect was not accompanied by a change in the size or morphology of individual bacteria (Engström et al, 2015). However, it was unclear whether KSK120 affected inclusion size, bacterial replication or both.…”

“…Current data indicate that the G-6P transporter UhpC is targeted by KSK120 and that this compound may block import of G-6P into C. trachomatis. and interestingly, we also observed that KSK120 might decrease bacterial replication without affecting the expansion of formed C. trachomatis inclusions (Engström et al, 2015). Thus, to potentially reveal novel insights on the regulation of inclusion expansion, we have further characterized the effect of compound KSK120 on C. trachomatis infections.…”

“…Therefore, it is likely not appropriate to use inclusion size as a correlate for infectious progeny output (Ouellette and Carabeo, 2010), as we herein observe that the inclusions expand during almost complete absence of infectious progeny generation (10 M KSK120, Fig. 2B and Engström et al, 2015).…”

“…Cycloheximide was excluded in all experiments. KSK120 was synthesized and handled as previously described (Engström et al, 2015). KSK120 was dissolved in dimethyl sulfoxide (DMSO, Sigma) to a final concentration of 20 mM, and stored at room temperature unexposed to light for a period of up to 2 months.…”

“…Our previous data showed that KSK120 blocked C. trachomatis infectivity by targeting bacterial glucose metabolism (Engström et al, 2015). Because C. trachomatis has a complex developmental cycle, which includes its transition between an infectious elementary body (EB) and a replicative reticulate body (RB), the blockade of infectivity caused by KSK120 could potentially be explained by: Fig.…”