In Dickeya dadantii, the Type II Secretion System (T2SS) is covalently attached to the bacterial cell wall. - Archive ouverte HAL Accéder directement au contenu
Poster De Conférence Année : 2023

In Dickeya dadantii, the Type II Secretion System (T2SS) is covalently attached to the bacterial cell wall.

Résumé

Dickeya dadantii is a broad-spectrum phytopathogenic γ-proteobacterium that provokes soft rot disease in various plants. D. dadantii pathogenicity is mainly caused by an arsenal of plant cell-wall degrading enzymes secreted by the Type II Secretion System (T2SS) named Out. The Out system is a multiprotein complex that spans the cell envelope. Recently, we showed that OutB, an inner membrane T2SS component plays an important scaffolding role and deletion of outB causes a striking reduction of pectinase secretion and virulence of D. dadantii (1). Here, we show that in D. dadantii, OutB is covalently attached to the PG. In fact, in the bacteria of genus Dickeya, the C-terminal sequence of OutB mimics that of Braun’s lipoprotein (Lpp). Until recently, Lpp has remained the unique known example of a protein covalently attached to the PG in Gram-negative bacteria (2,3,4). We investigated the molecular mechanisms of OutB attachment to peptidoglycan (PG) and possible implication of this phenomenon in the virulence of D. dadantii. The covalent attachment of OutB was demonstrated after extraction, purification and analysis of the PG of D. dadantii by Western blot. Then, we characterized the enzymes implicated and identified the region and residues of OutB important for covalent attachment to PG. We showed that the two C-terminal lysines of OutB are involved in its attachment to PG and that two L,D-transpeptidases, Ldt03 and Ldt84, catalyze this process. Further mass spectrometry analysis will be shortly performed to validate these data. These results suggest that the covalent attachment of OutB and with it, the whole T2SS, to PG allows a better stabilization of the secretion system in the bacterial envelope. This study shows that the phenomenon of covalent attachment of proteins to PG in proteobacteria is not limited to Lpp and could be more widespread and remains largely unexplored. 1. Zhang S, et al., (2022). mBio, doi : 10.1128/mbio.00253-22 2. Asmar, A. T., & Collet, J. F. (2018). FEMS microbiology letters, 365(18), doi : 10.1093/femsle/fny199 3. Sandoz KM, et al., (2021). Nature Microbiology, 6(1):19-26, doi : 10.1038/s41564-020-00798-42. 4. Godessart, P., et al., (2021). Nature Microbiology, 6(1), 27-33, doi : 10.1038/s41564-020-00799-3
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hal-04309264 , version 1 (27-11-2023)

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  • HAL Id : hal-04309264 , version 1

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Vladimir E Shevchik, Xavier Nicolai. In Dickeya dadantii, the Type II Secretion System (T2SS) is covalently attached to the bacterial cell wall.. 16th Plant Bacteria Meeting, Mar 2023, Aussios, France. 2023. ⟨hal-04309264⟩
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