Identification of essential genes in Coxiella burnetii

Abstract

Coxiella burnetii is an intracellular pathogen responsible for causing Q fever in humans, a disease with varied presentations ranging from a mild flu-like sickness to a debilitating illness that can result in endocarditis. The intracellular lifestyle of C. burnetii is unique, residing in an acidic phagolysosome-like compartment within host cells. An understanding of the core molecular biology of C. burnetii will greatly increase our understanding of C. burnetii growth, survival and pathogenesis. We used transposon-directed insertion site sequencing (TraDIS) to reveal C. burnetii Nine Mile Phase II genes fundamental for growth and in vitro survival. Screening a transposon library containing >10 000 unique transposon mutants revealed 512 predicted essential genes. Essential routes of synthesis were identified for the mevalonate pathway, as well as peptidoglycan and biotin synthesis. Some essential genes identified (e.g. predicted type IV secretion system effector genes) are typically considered to be associated with C. burnetii virulence, a caveat concerning the axenic media used in the study. Investigation into the conservation of the essential genes identified revealed that 78 % are conserved across all C. burnetii strains sequenced to date, which probably play critical functions. This is the first report of a whole genome transposon screen in C. burnetii that has been undertaken for the identification of essential genes.

Recent advances in genetic systems in obligate intracellular human-pathogenic bacteria

“…These two studies both confirmed that the Dot/Icm T4BSS system is essential for growth of C. burnetii in host cells and were only feasible owing to axenic growth. The next four publications using Himar1 transposition in C. burnetii generated transposon libraries for screening of potential virulence factors (Weber et al, 2013;Martinez et al, 2014;Newton et al, 2014;Metters et al, 2023). These libraries consisted of >20 (Weber et al, 2013), 3840 (Newton et al, 2014), >3000 (Martinez et al, 2014), and 10,000 (Metters et al, 2023) individual transposon insertions.…”

“…The next four publications using Himar1 transposition in C. burnetii generated transposon libraries for screening of potential virulence factors (Weber et al, 2013;Martinez et al, 2014;Newton et al, 2014;Metters et al, 2023). These libraries consisted of >20 (Weber et al, 2013), 3840 (Newton et al, 2014), >3000 (Martinez et al, 2014), and 10,000 (Metters et al, 2023) individual transposon insertions. Three libraries were generated using a single Himar1 plasmid system (Weber et al, 2013;Newton et al, 2014;Metters et al, 2023), whereas the third library was generated using a two plasmid Himar1 system (Martinez et al, 2014).…”

“…These libraries consisted of >20 (Weber et al, 2013), 3840 (Newton et al, 2014), >3000 (Martinez et al, 2014), and 10,000 (Metters et al, 2023) individual transposon insertions. Three libraries were generated using a single Himar1 plasmid system (Weber et al, 2013;Newton et al, 2014;Metters et al, 2023), whereas the third library was generated using a two plasmid Himar1 system (Martinez et al, 2014). Weber et al described the identification of 20 transposon insertions in T4BSS effector genes, 10 of which had defects in intracellular growth and CCV formation (Weber et al, 2013).…”

“…These data helped to identify OmpA as the first C. burnetii invasion. The most recent mutant library garnered >10,000 individual mutants and is the first study to look at identifying essential genes in C. burnetii (Metters et al, 2023). A total of 511 genes were predicted to be essential.…”

Zoonotic Diseases Caused by Mastitic Milk

“…Two different Antigenic forms have been found of C. burnetti and are distinguished on the basis of surface lipopolysaccharides. Phase I is the virulent type that completes the LPS on their surface, while the phase II is non virulent, having incomplete LPS and is non virulent (Metters et al 2023).…”