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Activity and Crystal Structure of the Adherent-Invasive Escherichia coli Tle3/Tli3 T6SS Effector/Immunity Complex Determined Using an AlphaFold2 Predicted Model

Authors :
Thi Thu Hang Le
Christine Kellenberger
Marie Boyer
Pierre Santucci
Nicolas Flaugnatti
Eric Cascales
Alain Roussel
Stéphane Canaan
Laure Journet
Christian Cambillau
Source :
International Journal of Molecular Sciences, Vol 24, Iss 2, p 1740 (2023)
Publication Year :
2023
Publisher :
MDPI AG, 2023.

Abstract

The type VI secretion system (T6SS) delivers enzymatic effectors into target cells to destroy them. Cells of the same strain protect themselves against effectors with immunity proteins that specifically inhibit effectors. Here, we report the identification and characterization of a Tle3 phospholipase effector and its cognate immunity protein Tli3—an outer membrane lipoprotein from adherent-invasive Escherichia coli (AIEC). Enzymatic assays demonstrate that purified Tle3AIEC has a phospholipase A1, and not A2, activity and that its toxicity is neutralized by the cognate immunity protein Tli3AIEC. Tli3AIEC binds Tle3 in a 1:1 stoichiometric ratio. Tle3AIEC, Tli3AIEC and the Tle3AIEC-Tli3AIEC complex were purified and subjected to crystallization. The Tle3AIEC-Tli3AIEC complex structure could not be solved by SeMet phasing, but only by molecular replacement when using an AlphaFold2 prediction model. Tle3AIEC exhibits an α/β-hydrolase fold decorated by two protruding segments, including a N-terminus loop. Tli3AIEC displays a new fold of three stacked β-sheets and a protruding loop that inserts in Tle3AIECcatalytic crevice. We showed, experimentally, that Tle3AIEC interacts with the VgrG AIEC cargo protein and AlphaFold2 prediction of the VgrGAIEC-Tle3AIEC complex reveals a strong interaction between the VgrGAIEC C-terminus adaptor and Tle3AIEC N-terminal loop.

Details

Language :
English
ISSN :
14220067 and 16616596
Volume :
24
Issue :
2
Database :
Directory of Open Access Journals
Journal :
International Journal of Molecular Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.6e79ee0e65a044bc945416d9a75be0b7
Document Type :
article
Full Text :
https://doi.org/10.3390/ijms24021740