Anchoring the T6SS to the cell wall: Crystal structure of the peptidoglycan binding domain of the TagL accessory protein

van Son Nguyen (1) , Silvia Spinelli (1) , E. Cascales (2) , Alain Roussel (1) , Christian Cambillau (1) , Philippe Leone (1)

1 AFMB - Architecture et fonction des macromolécules biologiques
2 LISM - Laboratoire d'ingénierie des systèmes macromoléculaires

The type VI secretion system (T6SS) is a widespread mechanism of protein delivery into target cells, present in more than a quarter of all sequenced Gram-negative bacteria. The T6SS constitutes an important virulence factor, as it is responsible for targeting effectors in both prokaryotic and eukaryotic cells. The T6SS comprises a tail structure tethered to the cell envelope via a trans-envelope complex. In most T6SS, the membrane complex is anchored to the cell wall by the TagL accessory protein. In this study, we report the first crystal structure of a peptidoglycan-binding domain of TagL. The fold is conserved with members of the OmpA/Pal/MotB family, and more importantly, the peptidoglycan binding site is conserved. This structure further exemplifies how proteins involved in anchoring to the cell wall for different cellular functions rely on an interaction network with peptidoglycan strictly conserved.

Mots clés: Secretion systems; Cell walls; Peptidoglycans; Crystal structure; Outer membrane proteins; DNA cloning; Molecular structure; Sequence alignment

Domaines: Sciences du Vivant [q-bio]

van Son Nguyen, Silvia Spinelli, E. Cascales, Alain Roussel, Christian Cambillau, et al.. Anchoring the T6SS to the cell wall: Crystal structure of the peptidoglycan binding domain of the TagL accessory protein. PLoS ONE, 2021, 16 (7), pp.e0254232. ⟨10.1371/journal.pone.0254232⟩. ⟨hal-03336427⟩