4n88 | pdb_00004n88

Crystal structure of Tse3-Tsi3 complex with calcium ion

spinqualitylabelsall models 4n88, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4n88 is a 4 chain structure with sequence from Pseudomonas aeruginosa PAO1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TSE3_PSEAE Toxin secreted by the H1 type VI (H1-T6SS) secretion system into the periplasm of recipient cells. Degrades peptidoglycan via muramidase activity thereby helping itself to compete with other bacteria (PubMed:21776080). To protect itself, the bacterium synthesizes immunity protein Tsi3 that specifically interacts with and inactivates cognate toxin (PubMed:24025333). Publication Abstract from PubMed The opportunistic pathogen Pseudomonas aeruginosa uses the type VI secretion system (T6SS) to deliver the muramidase Tse3 into the periplasm of rival bacteria to degrade their peptidoglycan (PG). Concomitantly, P. aeruginosa uses the periplasm-localized immunity protein Tsi3 to prevent potential self-intoxication caused by Tse3, and thus gains an edge over rival bacteria in fierce niche competition. Here, we report the crystal structures of Tse3 and the Tse3-Tsi3 complex. Tse3 contains an annexin repeat-like fold at the N-terminus and a G-type lysozyme fold at the C-terminus. One loop in the N-terminal domain (Loop 12) and one helix (alpha9) from the C-terminal domain together anchor Tse3 and the Tse3-Tsi3 complex to membrane in a calcium-dependent manner in vitro, and this membrane-binding ability is essential for Tse3's activity. In the C-terminal domain, a Y-shaped groove present on the surface likely serves as the PG-binding site. Two calcium-binding motifs are also observed in the groove and these are necessary for Tse3 activity. In the Tse3-Tsi3 structure, three loops of Tsi3 insert into the substrate-binding groove of Tse3, and three calcium ions present at the interface of the complex are indispensable for the formation of the Tse3-Tsi3 complex. Structural insights into the T6SS effector protein Tse3 and the Tse3-Tsi3 complex from Pseudomonas aeruginosa reveal a calcium-dependent membrane-binding mechanism.,Lu D, Shang G, Zhang H, Yu Q, Cong X, Yuan J, He F, Zhu C, Zhao Y, Yin K, Chen Y, Hu J, Zhang X, Yuan Z, Xu S, Hu W, Cang H, Gu L Mol Microbiol. 2014 Apr 14. doi: 10.1111/mmi.12616. PMID:24724564 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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