Integrating Chemical Mutagenesis and Whole-Genome Sequencing as a Platform for Forward and Reverse Genetic Analysis of Chlamydia

• A fully sequenced collection of chemically induced C. trachomatis mutants was generated
• Analysis of nonsense mutations reveals plasticity in C. trachomatis central metabolism
• A genetic screen found InaC modulates actin localization at the Chlamydia vacuole
• InaC modulates Golgi positioning and recruits host ARF GTPases and 14-3-3 proteins

SummaryGene inactivation by transposon insertion or allelic exchange is a powerful approach to probe gene function. Unfortunately, many microbes, including Chlamydia, are not amenable to routine molecular genetic manipulations. Here we describe an arrayed library of chemically induced mutants of the genetically intransigent pathogen Chlamydia trachomatis, in which all mutations have been identified by whole-genome sequencing, providing a platform for reverse genetic applications. An analysis of possible loss-of-function mutations in the collection uncovered plasticity in the central metabolic properties of this obligate intracellular pathogen. We also describe the use of the library in a forward genetic screen that identified InaC as a bacterial factor that binds host ARF and 14-3-3 proteins and modulates F-actin assembly and Golgi redistribution around the pathogenic vacuole. This work provides a robust platform for reverse and forward genetic approaches in Chlamydia and should serve as a valuable resource to the community.

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