Structural basis of bacterial defense against g-type lysozyme-based innate immunity

• Published in: Cellular and Molecular Life Sciences
• Main Authors: Leysen, Seppe, Vanderkelen, Lise, Weeks, Stephen, Michiels, Chris, Strelkov, Sergei
• Format: Article in Journal/Newspaper
• Language: English
• Published: Birkhäuser Verlag 2013
• Subjects: Science & Technology; Life Sciences & Biomedicine; Biochemistry & Molecular Biology; Cell Biology; Lysozyme inhibitor; PliG; Lysozyme; Innate immunity; Inhibitory complex; Crystal structure; GOOSE-TYPE LYSOZYMES; ESCHERICHIA-COLI; INHIBITOR; SCATTERING; CHITINASE; PROTEINS; COMPLEX; SYSTEM; HEALTH; MODEL; Animals; Crystallography; Escherichia coli; Escherichia coli Proteins; Immunity; Innate; Models; Molecular; Muramidase; Protein Conformation; Salmo salar; 0601 Biochemistry and Cell Biology; 0606 Physiology; 1103 Clinical Sciences; 3101 Biochemistry and cell biology; 3205 Medical biochemistry and metabolomics; 3211 Oncology and carcinogenesis; Atlantic salmon
• Online Access: https://lirias.kuleuven.be/handle/123456789/362011; https://doi.org/10.1007/s00018-012-1184-1; https://pubmed.ncbi.nlm.nih.gov/23086131

Gram-negative bacteria can produce specific proteinaceous inhibitors to defend themselves against the lytic action of host lysozymes. So far, four different lysozyme inhibitor families have been identified. Here, we report the crystal structure of the Escherichia coli periplasmic lysozyme inhibitor of g-type lysozyme (PliG-Ec) in complex with Atlantic salmon g-type lysozyme (SalG) at a resolution of 0.95 Å, which is exceptionally high for a complex of two proteins. The structure reveals for the first time the mechanism of g-type lysozyme inhibition by the PliG family. The latter contains two specific conserved regions that are essential for its inhibitory activity. The inhibitory complex formation is based on a double 'key-lock' mechanism. The first key-lock element is formed by the insertion of two conserved PliG regions into the active site of the lysozyme. The second element is defined by a distinct pocket of PliG accommodating a lysozyme loop. Computational analysis indicates that this pocket represents a suitable site for small molecule binding, which opens an avenue for the development of novel antibacterial agents that suppress the inhibitory activity of PliG. sponsorship: Access to the synchrotron beamlines PROX-IMA1 at Soleil and X33 at the Deutsches Elektronen-Synchrotron is gratefully acknowledged, with a special 'thank you' to Dr. Andrew Thompson for help with ultrahigh-resolution data collection. We also thank Dr. Pavel Afonine for advice on crystallographic refinement. S. Leysen holds a doctoral grant from the K.U. Leuven. L. Vanderkelen holds a doctoral fellowship from the Flemish Institute for the Promotion of Scientific Technological Research (IWT). This work was further financially supported by a Research Grant (G.0363.08) from the Research Foundation-Flanders (F.W.O.-Vlaanderen) and from the KU Leuven Research Fund (research project METH/07/03). (K.U. Leuven, Flemish Institute for the Promotion of Scientific Technological Research (IWT), Research Foundation-Flanders ...