A role for the ATP-dependent DNA ligase Lig E ofNeisseria gonorrhoeaein biofilm formation

Abstract

ABSTRACTThe ATP-dependent DNA ligase Lig E is present as an accessory DNA ligase in numerous proteobacterial genomes, including many disease-causing species. Here we have constructed a genomic Lig E knock-out in the obligate human pathogenNeisseria gonorrhoeaeand characterised its growth and infection characteristics. This demonstrates thatN. gonorrhoeaeLig E is a non-essential gene and its deletion does not cause defects in replication or survival of DNA-damaging stressors. Knock-out strains were partially defective in biofilm formation on an artificial surface as well as adhesion to epithelial cells which coupled with the predicted extracellular/ periplasmic location of Lig E indicates a role in extracellular DNA joining. In addition toin vivocharacterisation, we have recombinantly expressed and assayedN. gonorrhoeaeLig E and determined the crystal structure of the enzyme-adenylate engaged with DNA substrate in an open non-catalytic conformation, providing insight into the binding dynamics of these minimal DNA ligases.