Xanthomonas immunity proteins protect against the cis-toxic effects of their cognate T4SS effectors

Author(s)

Oka, Gabriel U. ; Souza, Diorge P. ; Sgro, German G. ; Guzzo, Cristiane R. ; Dunger, German ; Farah, Chuck S.

• Document type: Journal article
• Source: EMBO REPORTS; v. 25, n. 3, p. 17-pg., 2024-03-12.

Abstract

Many bacteria kill rival species by translocating toxic effectors into target cells. Effectors are often encoded along with cognate immunity proteins that could (i) protect against "friendly-fire" (trans-intoxication) from neighboring sister cells and/or (ii) protect against internal cis-intoxication (suicide). Here, we distinguish between these two mechanisms in the case of the bactericidal Xanthomonas citri Type IV Secretion System (X-T4SS). We use a set of X. citri mutants lacking multiple effector/immunity protein (X-Tfe/X-Tfi) pairs to show that X-Tfis are not absolutely required to protect against trans-intoxication by wild-type cells. Our investigation then focused on the in vivo function of the lysozyme-like effector X-TfeXAC2609 and its cognate immunity protein X-TfiXAC2610. In the absence of X-TfiXAC2610, we observe X-TfeXAC2609-dependent and X-T4SS-independent accumulation of damage in the X. citri cell envelope, cell death, and inhibition of biofilm formation. While immunity proteins in other systems have been shown to protect against attacks by sister cells (trans-intoxication), this is an example of an antibacterial secretion system in which the immunity proteins are dedicated to protecting cells against cis-intoxication. (AU)

• FAPESP's process: 18/09277-9 - Investigation of the structural requirements for recognition of T4SS-related toxins by the coupling protein VirD4.
• Grantee: Gabriel Umaji Oka
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 11/22571-4 - Regulation of Xanthomonas citri Type IV pilus
• Grantee: Ricardo Germán Dunger
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/10577-0 - Biology of Bacteria and Bacteriophages Research Center
• Grantee: Shaker Chuck Farah
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/17303-7 - Structure and function of bacterial secretion systems
• Grantee: Shaker Chuck Farah
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/04294-1 - Structural and functional studies of the Xanthomonas citri Type IV Secretion System
• Grantee: Germán Gustavo Sgro
• Support Opportunities: Scholarships in Brazil - Post-Doctoral