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

Abstract: 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 ?-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 ?-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.

 Authorship: Amado E., Muth G., Arechaga I., Cabezón E.,

 Fuente: J Biol Chem. 2019 Mar 29;294(13):5050-5059

 Publisher: American Society for Biochemistry and Molecular Biology Inc.

 Publication date: 01/03/2019

 No. of pages: 20

 Publication type: Article

 DOI: 10.1074/jbc.RA119.007459

 ISSN: 0021-9258,1083-351X

 Spanish project: BFU2016-78521-R

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