ComF is a key mediator in single-stranded DNA transport and handling during natural transformation

Abstract

Natural transformation plays a major role in the spreading of antibiotic resistances and virulence factors. Whilst bacterial species display specificities in the molecular machineries allowing transforming DNA capture and integration into their genome, the ComF(C) protein is essential for natural transformation in all Gram- positive and - negative species studied. Despite this, its role remains largely unknown. Here, we show that Helicobacter pylori ComF is not only involved in DNA transport through the cell membrane, but it also required for the handling of the ssDNA once it is delivered into the cytoplasm. ComF crystal structure revealed the presence of a zinc-finger motif and a putative phosphoribosyl transferase domain, both necessary for its in vivo activity. ComF is a membrane-associated protein with affinity for single-stranded DNA. Collectively, our results suggest that ComF provides the link between the transport of the transforming DNA into the cytoplasm and its handling by the recombination machinery.

Genetic manipulation of candidate phyla radiation bacteria provides functional insights into microbial dark matter

“…Genes encoding the core components of the com DNA uptake system are conserved across CPR phyla, including the Saccharibacteria 5 . These consist of ComEC, the central membrane DNA conduit, DprA, a catalyst of Rec-mediated recombination, and ComFC, which binds ssDNA and links import to recombination [22][23][24] . Com proteins function in concert with type IV pili, which are also widely distributed in Saccharibacteria, and CPR bacteria more generally 5,23 .…”