The FtsK-like motor TraB is a DNA-dependent ATPase that forms higher-order assembliesThe FtsK-like motor TraB is a DNA-dependent ATPase that forms higher-order assembliesAmado E, Muth G, Arechaga I, Cabezón E.2019-03-28T23:00:00Z<h3>Abstract<br></h3><div> <br> </div><div>TraB is an FtsK-like DNA translocase responsible for conjugative plasmid transfer in mycelial Streptomyces Unlike other conjugative systems, which depend on a type IV secretion system, Streptomyces requires only TraB protein to transfer the plasmid as dsDNA. The γ-domain of this protein specifically binds to repeated 8-bp motifs on the plasmid sequence, following a mechanism that is reminiscent of the FtsK/SpoIIIE chromosome segregation system. In this work, we purified and characterized the enzymatic activity of TraB, revealing that it is a DNA-dependent ATPase that is highly stimulated by dsDNA substrates. Interestingly, we found that unlike the SpoIIIE protein, the γ-domain of TraB does not confer sequence-specific ATPase stimulation. We also found that TraB binds G-quadruplex DNA structures with higher affinity than TraB-recognition sequences (TRSs). An EM-based structural analysis revealed that TraB tends to assemble as large complexes comprising four TraB hexamers, which might be a prerequisite for DNA translocation across cell membranes. In summary, our findings shed light on the molecular mechanism used by the DNA-translocating motor TraB, which may be shared by other membrane-associated machineries involved in DNA binding and translocation.<br></div> <br><p><a href="">​J Biol Chem. 2019 Mar 29;294(13):5050-5059.</a><br></p>413