VirB7 and VirB9 Interactions Are Required for the Assembly and Antibacterial Activity of a Type IV Secretion System
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Publication date
2016-10-04
Authors
Oliveira, Luciana Coutinho
Souza, Diorge Paulo
Oka, Gabriel Umaji
Lima, Filipe da Silva
Oliveira, Ronaldo Junio
Favaro, Denize Cristina
Wienk, Hans
Boelens, R.
Farah, Chuck Shaker
Salinas, Roberto Kopke
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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.
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Oliveira, L C, Souza, D P, Oka, G U, Lima, F D S, Oliveira, R J, Favaro, D C, Wienk, H, Boelens, R, Farah, C S & Salinas, R K 2016, 'VirB7 and VirB9 Interactions Are Required for the Assembly and Antibacterial Activity of a Type IV Secretion System', Structure, vol. 24, no. 10, pp. 1707-1718. https://doi.org/10.1016/j.str.2016.07.015