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J Biol Chem. 2011 May 13;286(19):17376-82. doi: 10.1074/jbc.M110.208942. Epub 2011 Mar 24.

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

Author information

1
Departamento de Biología Molecular, Universidad de Cantabria and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), UC-IDICAN-CSIC, Santander 39011, Spain.

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.

PMID:
21454654
PMCID:
PMC3089579
DOI:
10.1074/jbc.M110.208942
[Indexed for MEDLINE]
Free PMC Article

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