title: 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.
authors: Departamento de Biología Molecular, Universidad de Cantabria and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), UC-IDICAN-CSIC, Santander 39011, Spain.
authors: Alejandro
authors: A
authors: Peña
authors: Jorge
authors: J
authors: Ripoll-Rozada
authors: Sandra
authors: S
authors: Zunzunegui
authors: Elena
authors: E
authors: Cabezón
authors: Fernando
authors: F
authors: de la Cruz
authors: Ignacio
authors: I
authors: Arechaga
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D058947:Bacterial Secretion Systems; D002462:Cell Membrane / Q000378:metabolism; D004798:Enzymes / Q000737:chemistry; D005816:Genetic Complementation Test; D006868:Hydrolysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D058947:Bacterial Secretion Systems; D004798:Enzymes; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases