Autoinhibitory regulation of TrwK, an essential VirB4 ATPase in type IV secretion systems. Autoinhibitory regulation of TrwK, an essential VirB4 ATPase in type IV secretion systems.Peña A, Ripoll-Rozada J, Zunzunegui S, Cabezón E, de la Cruz F, Arechaga I* J. Biol. Chem. 2011, 286(19), 17376-82. DOI:10.1074/jbc.M110.208942. 2011-06-15T22:00:00Z<p style="text-align:justify;">​<span class="ms-rteThemeFontFace-1 ms-rteFontSize-2" style="color:#000000;font-weight:bold;">Abstract</span></p><p style="color:#000000;margin-top:15px;margin-bottom:15px;padding:0px;border:0px;outline-style:none;font-size:12.800000190734863px;font-family:"open sans";line-height:1.5;vertical-align:baseline;text-align:justify;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">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 </span><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2" style="margin:0px;padding:0px;border:0px;outline-style:none;font-style:italic;line-height:inherit;vertical-align:baseline;">in vitro</span><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2"> 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.</span><br></p><p><a href="http://www.jbc.org/content/286/19/17376.full">​[pubmed]</a><br></p>29