A Legionella effector ADP-ribosyltransferase inactivates glutamate dehydrogenase

Abstract

ADP-ribosyltransferases (ARTs) are a widespread superfamily of enzymes frequently employed in pathogenic strategies of bacteria. Legionella pneumophila, the causative agent of Legionnaires disease, has acquired over 330 translocated effectors that showcase remarkable biochemical and structural diversity. Here we took a bioinformatic approach to search the Legionella effector repertoire for additional divergent members of the ART superfamily and identified an ART domain in Lpg0181. We show that L. pneumophila Lpg0181 targets a specific class of 120-kDa NAD+-dependent glutamate dehydrogenase (GDH) enzymes found in fungi and protists, including many natural hosts of Legionella. Lpg0181 targets a conserved arginine residue in the NAD+ -binding pocket of GDH, thereby blocking oxidative deamination of glutamate. While intracellular pathogens employ diverse virulence mechanisms to overcome host-limited nutrient availability, Lpg0181 is--to the best of our knowledge--the first example of a Legionella effector which directly targets a host metabolic enzyme.