Structure of shikimate kinase, anin vivoessential metabolic enzyme in the nosocomial pathogenAcinetobacter baumannii, in complex with shikimate

Abstract

Acinetobacter baumanniiis an opportunistic Gram-negative pathogen that is an important cause of healthcare-associated infections exhibiting high mortality rates. Clinical isolates of multidrug-resistant (MDR) and extremely drug-resistant (XDR)A. baumanniistrains are increasingly being observed. Compounding this concern is the dearth of new antibacterial agents in late-stage development that are effective against MDR and XDRA. baumannii. As part of an effort to address these concerns, two genes (aroAandaroC) of the shikimate pathway have previously been determined to be essential for the growth and survival ofA. baumanniiduring host infection (i.e.to be essentialin vivo). This study expands upon these results by demonstrating that theA. baumannii aroKgene, encoding shikimate kinase (SK), is also essentialin vivoin a rat soft-tissue infection model. The crystal structure ofA. baumanniiSK in complex with the substrate shikimate and a sulfate ion that mimics the binding interactions expected for the β-phosphate of ATP was then determined to 1.91 Å resolution and the enzyme kinetics were characterized. The flexible shikimate-binding domain and LID region are compared with the analogous regions in other SK crystal structures. The impact of structural differences and sequence divergence between SKs from pathogenic bacteria that may influence antibiotic-development efforts is discussed.