The FtsK-like motor TraB is a DNA-dependent ATPase that forms higher-order assemblies.

Eric Amado, Günther Muth, Ignacio Arechaga, Elena Cabezón

The Journal of biological chemistry 2019 Mar 29

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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. © 2019 Amado et al.

Citation

Eric Amado, Günther Muth, Ignacio Arechaga, Elena Cabezón. The FtsK-like motor TraB is a DNA-dependent ATPase that forms higher-order assemblies. The Journal of biological chemistry. 2019 Mar 29;294(13):5050-5059