7mu9

Publication Abstract from PubMed

Many soil-, water-, and plant-associated bacterial species from the orders Xanthomonadales, Burkholderales, and Neisseriales carry a type IV secretion system (T4SS) specialized in translocating effector proteins into other gram-negative species, leading to target cell death. These effectors, known as X-Tfes, carry a carboxyl-terminal domain of approximately 120 residues, termed XVIPCD, characterized by several conserved motifs and a glutamine-rich tail. Previous studies showed that the XVIPCD is required for interaction with the T4SS coupling protein VirD4 and for T4SS-dependent translocation. However, the structural basis of the XVIPCD-VirD4 interaction is unknown. Here, we show that the XVIPCD interacts with the central all-alpha domain of VirD4 (VirD4AAD). We used solution NMR spectroscopy to solve the structure of the XVIPCD of X-Tfe(XAC2609) from Xanthomonas citri and to map its interaction surface with VirD4AAD Isothermal titration calorimetry and in vivo Xanthomonas citri versus Escherichia coli competition assays using wild-type and mutant X-Tfe(XAC2609) and X-Tfe(XAC3634) indicate that XVIPCDs can be divided into two regions with distinct functions: the well-folded N-terminal region contains specific conserved motifs that are responsible for interactions with VirD4AAD, while both N- and carboxyl-terminal regions are required for effective X-Tfe translocation into the target cell. The conformational stability of the N-terminal region is reduced at and below pH 7.0, a property that may facilitate X-Tfe unfolding and translocation through the more acidic environment of the periplasm.

Structural basis for effector recognition by an antibacterial type IV secretion system.,Oka GU, Souza DP, Cenens W, Matsuyama BY, Cardoso MVC, Oliveira LC, da Silva Lima F, Cuccovia IM, Guzzo CR, Salinas RK, Farah CS Proc Natl Acad Sci U S A. 2022 Jan 4;119(1). pii: 2112529119. doi:, 10.1073/pnas.2112529119. PMID:34983846^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.