3WA5

Crystal Structure of type VI peptidoglycan muramidase effector Tse3 in complex with its cognate immunity protein Tsi3

Summary for 3WA5

• Entry DOI: 10.2210/pdb3wa5/pdb
• Descriptor: Type VI secretion exported 3, Tse3-specific immunity protein, 1,2-ETHANEDIOL, ... (5 entities in total)
• Functional Keywords: protein-protein complex, muramidase, hydrolase
• Biological source: Pseudomonas aeruginosa; More
• Total number of polymer chains: 2
• Total formula weight: 63288.17

Authors

Ding, J.,Wang, T.,Liu, W.,Wang, D.C. (deposition date: 2013-04-26, release date: 2013-10-02, Last modification date: 2024-11-20)

Primary citation

Wang, T.,Ding, J.,Zhang, Y.,Wang, D.C.,Liu, W.
Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein.
Acta Crystallogr.,Sect.D, 69:1889-1900, 2013

PubMed Abstract: The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for niches via amidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1-Tsi1 has been structurally characterized. Here, the structure of the Tse3-Tsi3 complex is reported at 1.9 Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a β-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3-Tsi3 effector-immunity pair.

PubMed: 24100309
DOI: 10.1107/S090744491301576X

Experimental method

X-RAY DIFFRACTION (1.9 Å)