A multiomic approach to defining the essential genome of the globally important pathogen Corynebacterium diphtheriae.

Diphtheria is a respiratory disease caused by Corynebacterium diphtheriae. While the toxin-based vaccine has helped control outbreaks of the disease since the mid-20^th century there has been an increase in cases in recent years, including systemic infections caused by non-toxigenic C. diphtheriae strains. Here we describe the first study of gene essentiality in C. diphtheriae, providing the most-dense Transposon Directed Insertion Sequencing (TraDIS) library in the phylum Actinobacteriota. This high-density library has allowed the identification of conserved genes across the genus and phylum with essential function and enabled the elucidation of essential domains within the resulting proteins including those involved in cell envelope biogenesis. Validation of these data through protein mass spectrometry identified hypothetical and uncharacterized proteins in the proteome which are also represented in the vaccine. These data are an important benchmark and useful resource for the Corynebacterium, Mycobacterium, Nocardia and Rhodococcus research community. It enables the identification of novel antimicrobial and vaccine targets and provides a basis for future studies of Actinobacterial biology. Author summary: Corynebacterium diphtheriae causes both toxin-mediated diphtheria and non-toxigenic invasive infections. Despite a vaccine to protect against diphtheria, case numbers for both invasive and diphtherial disease have increased over the last decade. Furthermore, an increase in antibiotic resistant strains are being isolated from patients. It's clear that additional treatment strategies for this organism will be needed in the future. Using high-throughput mutagenesis, this work presents the densest library of mutants for any Corynebacterium sp.. This work identifies the essential genome of C. diphtheriae; an important classification as these genes are often the target of therapeutic intervention. We identify highly conserved genes and species-specific genes unique to pathogens. This data presents an important benchmark and focus for the future development of therapeutic options. Of particular significance is the identification of uncharacterized, conserved proteins within the Diphtheria vaccine. [ABSTRACT FROM AUTHOR]