DprA from Neisseria meningitidis: properties and role in natural competence for transformation

DNA processing chain A (DprA) is a DNA-binding protein that is ubiquitous in bacteria and expressed in some archaea. DprA is active in many bacterial species that are competent for transformation of DNA, but its role in Neisseriameningitidis (Nm) is not well characterized. An Nm mutant lacking DprA was constructed, and the phenotypes of the wild-type and ΔdprA mutant were compared. The salient feature of the phenotype of dprA null cells is the total lack of competence for genetic transformation shown by all of the donor DNA substrates tested in this study. Here, Nm wild-type and dprA null cells appeared to be equally resistant to genotoxic stress. The gene encoding DprA(Nm) was cloned and overexpressed, and the biological activities of DprA(Nm) were further investigated. DprA(Nm) binds ssDNA more strongly than dsDNA, but lacks DNA uptake sequence-specific DNA binding. DprA(Nm) dimerization and interaction with the C-terminal part of the single-stranded binding protein SSB(Nm)were demonstrated. dprA is co-expressed with smg, a downstream gene of unknown function, and the gene encoding topoisomerase 1, topA.