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

Walldén, Karin and Williams, Robert and Yan, Jun and Lian, Pei W. and Wang, Luchun and Thalassinos, Konstantinos and Orlova, Elena and Waksman, Gabriel (2012) Structure of the VirB4 ATPase, alone and bound to the core complex of a type IV secretion system. Proceedings of the National Academy of Sciences of the United States of America 109 (28), pp. 11348-11353. ISSN 0027-8424.

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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.

Item Type: Article
Keyword(s) / Subject(s): macromolecular assembly, structural biology, conjugation
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 02 Jul 2012 08:28
Last Modified: 11 Oct 2016 15:26

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