VirB7 and VirB9 Interactions Are Required for the Assembly and Antibacterial Activity of a Type IV Secretion System.
Oliveira, L.C., Souza, D.P., Oka, G.U., Lima, F.D., Oliveira, R.J., Favaro, D.C., Wienk, H., Boelens, R., Farah, C.S., Salinas, R.K.(2016) Structure 24: 1707-1718
- PubMed: 27594685
- DOI: https://doi.org/10.1016/j.str.2016.07.015
- Primary Citation of Related Structures:
2N01 - PubMed Abstract:
The type IV secretion system (T4SS) from the phytopathogen Xanthomonas citri (Xac) is a bactericidal nanomachine. The T4SS core complex is a ring composed of multiple copies of VirB7-VirB9-VirB10 subunits. Xac-VirB7 contains a disordered N-terminal tail (VirB7 NT ) that recognizes VirB9, and a C-terminal domain (VirB7 CT ) involved in VirB7 self-association. Here, we show that VirB7 NT forms a short β strand upon binding to VirB9 and stabilizes it. A tight interaction between them is essential for T4SS assembly and antibacterial activity. Abolishing VirB7 self-association or deletion of the VirB7 C-terminal domain impairs this antibacterial activity without disturbing T4SS assembly. These findings reveal protein interactions within the core complex that are critical for the stability and activity of a T4SS.
Organizational Affiliation:
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil.