Structural basis for effector recognition by an antibacterial type IV secretion system
Gabriel Umaji Oka, Diorge P. Souza, William Cenens, Bruno Y. Matsuyama, Marcus V. C. Cardoso, Luciana Coutinho de Oliveira, Filipe S. Lima, Iolanda Midea Cuccovia, Cristiane Rodrigues Guzzo, Roberto Köpke Salinas, Chuck S. Farah
Abstract
Significance Type IV secretion systems (T4SSs) have been studied for more than 70 y because of their roles in mediating horizontal DNA transfer, responsible for the spread of antibiotic resistance, and the injection of virulence factors into animal and plant hosts. Another important function is the contact-dependent injection of toxic effectors into competing bacteria of different species during bacterial warfare. The present study reveals how T4SSs use a specific domain of the VirD4 coupling protein to recruit antibacterial toxins for secretion by recognizing conserved carboxyl-terminal secretion signal domains. The molecular structure of the secretion signal domain described in this work will serve as a model for thousands of homologs encountered in several hundred distinct bacterial species.