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The hexameric structure of a conjugative VirB4 protein ATPase provides new insights for a functional and phylogenetic relationship with DNA translocases

Abstract: VirB4 proteins are ATPases essential for pilus biogenesis and protein transport in type IV secretion systems. These proteins contain a motor domain that shares structural similarities with the motor domains of DNA translocases, such as the VirD4/TrwB conjugative coupling proteins and the chromosome segregation pump FtsK. Here, we report the three-dimensional structure of full-length TrwK, the VirB4 homologue in the conjugative plasmid R388, determined by single-particle electron microscopy. The structure consists of a hexameric double ring with a barrel-shaped structure. The C-terminal half of VirB4 proteins shares a striking structural similarity with the DNA translocase TrwB. Docking the atomic coordinates of the crystal structures of TrwB and FtsK into the EM map revealed a better fit for FtsK. Interestingly, we have found that like TrwB, TrwK is able to bind DNA with a higher affinity for G4 quadruplex structures than for single-stranded DNA. Furthermore, TrwK exerts a dominant negative effect on the ATPase activity of TrwB, which reflects an interaction between the two proteins. Our studies provide new insights into the structure-function relationship and the evolution of these DNA and protein translocases.

 Authorship: Peña A., Matilla I., Martín-Benito J., Valpuesta J.M., Carrascosa J.L., De La Cruz F., Cabezón E., Arechaga I.,

 Fuente: Journal of Biological Chemistry, 2012, 287(47), 39925-32

 Publisher: American Society for Biochemistry and Molecular Biology Inc.

 Year of publication: 2012

 No. of pages: 8

 Publication type: Article

 DOI: 10.1074/jbc.M112.413849

 ISSN: 0021-9258,1083-351X

 Publication Url: https://doi.org/10.1074/jbc.M112.413849

Autoría

ALEJANDRO PEÑA ONTALVILLA

MARIA INMACULADA MATILLA FERNANDEZ

MARTÍN-BENITO, JAIME

VALPUESTA, JOSÉ M.

CARRASCOSA, JOSÉ L.