VirB7 and VirB9 Interactions Are Required for the Assembly and Antibacterial Activity of a Type IV Secretion System

Author(s)

Oliveira, Luciana Coutinho ; Souza, Diorge Paulo ; Oka, Gabriel Umaji ; Lima, Filipe da Silva ; Oliveira, Ronaldo Junio ; Favaro, Denize Cristina ; Wienk, Hans ; Boelens, Rolf ; Farah, Chuck Shaker ; Salinas, Roberto Kopke

• Document type: Journal article
• Source: Structure; v. 24, n. 10, p. 1707-1718, OCT 4 2016.
• Web of Science Citations: 3

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 beta 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. (AU)

• FAPESP's process: 13/17883-2 - Structure and dynamics of the Na+/Ca2+ exchanger from Drosophila melanogaster
• Grantee: Roberto Kopke Salinas
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/07777-5 - Cyclic di-GMP signaling and the Type IV macromolecule secretion system in Xanthomonas citri
• Grantee: Shaker Chuck Farah
• Support Opportunities: Research Projects - Thematic Grants