Agrobacterium tumefaciens VirB8 structure reveals potential protein-protein interaction sites.
Bacterial type IV secretion systems (T4SS) translocate DNA and/or proteins to recipient cells, thus providing a mechanism for conjugative transfer of genetic material and bacterial pathogenesis. Here we describe the first structure of a core component from the archetypal Agrobacterium tumefaciens T4SS: the 2.2-A resolution crystal structure of the VirB8 periplasmic domain (pVirB8(AT)). VirB8 forms a dimer in the crystal, and we identify residues likely important for stabilization of the dimer interface. Structural comparison of pVirB8(AT) with Brucella suis VirB8 confirms that the monomers have a similar fold. In addition, the pVirB8(AT) dimer superimposes very closely on the B. suis VirB8 dimer, supporting the proposal that dimer formation in the crystal reflects self-interactions that are biologically significant. The evolutionary conservation level for each residue was obtained from a data set of 84 VirB8 homologs and projected onto the protein structure to indicate conserved surface patches that likely contact other T4SS proteins.
Molecular Biophysics Group, Council for the Central Laboratory of the Research Councils Daresbury Laboratory, Warrington WA4 4AD, United Kingdom.
Susan
S
Bailey
Doyle
D
Ward
Rebecca
R
Middleton
J Gunter
JG
Grossmann
Patricia C
PC
Zambryski
D016960:Agrobacterium tumefaciens / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D019281:Dimerization; D008969:Molecular Sequence Data; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D021381:Protein Transport
D001426:Bacterial Proteins