4eq8

Publication Abstract from PubMed

Tse1, an effector protein produced by Pseudomonas aeruginosa, is an amidase hydrolyzing gamma-D-glutamyl-L-meso-diaminopimelic acid (gamma-D-glutamyl-DAP) linkage of the peptide bridge of peptidoglycan. P. aeruginosa injects Tse1 into the periplasm of recipient cells, degrading their peptidoglycan, thereby helping itself to compete with other bacteria. Meanwhile, to protect itself from injury by Tse1, P. aeruginosa expresses the cognate immunity protein Tsi1 in its own periplasm to inactivate Tse1. In the present study, we report the crystal structures of Tse1 and Tse1 (6-148)-Tsi1 (20-end) complex at 1.4 A and 1.6 A resolutions, respectively. The Tse1 structure adopts a classical papain-like alpha+beta fold. A Cys-His catalytic diad is identified in the reaction centre of Tse1 by structural comparison and mutagenesis studies. Tsi1 binds Tse1 tightly. The HI loop (middle finger tip) from Tsi1 inserts into the large pocket of Y-shaped groove on the surface of Tse1, and CD, EF, JK and LM loops (thumb, index finger, ring finger and little finger tips) interact with Tse1, thus blocking the binding of enzyme to peptidoglycan. The catalytic and inhibition mechanisms give new insights into how P. aeruginosa competes with others and protects itself..

Structural insight into functioning of Pseudomonas aeruginosa peptidoglycan-hydolase Tse1 and its immunity protein Tsi1.,Shang G, Liu X, Lu D, Zhang J, Li N, Zhu C, Liu S, Yu Q, Zhao Y, Zhang H, Hu J, Cang H, Xu S, Gu L Biochem J. 2012 Aug 29. PMID:22931054^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.