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Autoinhibitory regulation of TrwK, an essential VirB4 ATPase in type IV secretion systems

Abstract: Type IV secretion systems (T4SS) mediate the transfer of DNA and protein substrates to target cells. TrwK, encoded by the conjugative plasmid R388, is a member of the VirB4 family, comprising the largest and most conserved proteins of T4SS. In a previous work we demonstrated that TrwK is able to hydrolyze ATP. Here, based on the structural homology of VirB4 proteins with the DNA-pumping ATPase TrwB coupling protein, we generated a series of variants of TrwK where fragments of the C-terminal domain were sequentially truncated. Surprisingly, the in vitro ATPase activity of these TrwK variants was much higher than that of the wild-type enzyme. Moreover, addition of a synthetic peptide containing the amino acid residues comprising this C-terminal region resulted in the specific inhibition of the TrwK variants lacking such domain. These results indicate that the C-terminal end of TrwK plays an important regulatory role in the functioning of the T4SS.

 Authorship: Peña A., Ripoll-Rozada J., Zunzunegui S., Cabezón E., De La Cruz F., Arechaga I.,

 Fuente: Journal of Biological Chemistry, 2011, 286(19), 17376-82

 Publisher: American Society for Biochemistry and Molecular Biology Inc.

 Year of publication: 2011

 No. of pages: 7

 Publication type: Article

 DOI: 10.1074/jbc.M110.208942

 ISSN: 0021-9258,1083-351X

 Spanish project: BFU2008-00806

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