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Structure of the VirB4 ATPase, alone and bound to the core complex of a type IV secretion system

DOI: 10.1073/pnas.1201428109 DOI Help
PMID: 22745169 PMID Help

Authors: K. Wallden (Department of Biological Sciences, Birkbeck, U.K.) , R. Williams (Department of Biological Sciences, Birkbeck, U.K.) , J. Yan (University College London) , P. W. Lian (Department of Biological Sciences, Birkbeck, U.K.) , L. Wang (Department of Biological Sciences, Birkbeck, U.K.) , K. Thalassinos (University College London, U.K.) , E. V. Orlova (University College London, U.K.) , G. Waksman (University College London, U.K.)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Proceedings Of The National Academy Of Sciences , VOL 109 (28) , PAGES 11348 - 11353

State: Published (Approved)
Published: July 2012
Diamond Proposal Number(s): 7197

Abstract: Type IV secretion (T4S) systems mediate the transfer of proteins and DNA across the cell envelope of bacteria. These systems play important roles in bacterial pathogenesis and in horizontal transfer of antibiotic resistance. The VirB4 ATPase of the T4S system is essential for both the assembly of the system and substrate transfer. In this article, we present the crystal structure of the C-terminal domain of Thermoanaerobacter pseudethanolicus VirB4. This structure is strikingly similar to that of another T4S ATPase, VirD4, a protein that shares only 12% sequence identity with VirB4. The VirB4 domain purifies as a monomer, but the full-length protein is observed in a monomer-dimer equilibrium, even in the presence of nucleotides and DNAs. We also report the negative stain electron microscopy structure of the core complex of the T4S system of the Escherichia coli pKM101 plasmid, with VirB4 bound. In this structure, VirB4 is also monomeric and bound through its N-terminal domain to the core’s VirB9 protein. Remarkably, VirB4 is observed bound to the side of the complex WHERE it is ideally placed to play its known regulatory role in substrate transfer.

Journal Keywords: Bacterial; Binding; Crystallization; Crystallography; X-Ray; DNA; Bacterial; Escherichia; Macromolecular; Magnesium; Mass; Microscopy; Electron; Models; Biological; Nucleotides; Plasmids; Protein; Virulence Factors

Subject Areas: Biology and Bio-materials


Instruments: I02-Macromolecular Crystallography , I04-Macromolecular Crystallography