MagC is a NplC/P60‐like member of the α‐2‐macroglobulin Mag complex of Pseudomonas aeruginosa that interacts with peptidoglycan

Abstract

Bacterial α‐2 macroglobulins (A2Ms) structurally resemble the large spectrum protease inhibitors of the eukaryotic immune system. In Pseudomonas aeruginosa, MagD acts as an A2M and is expressed within a six‐gene operon encoding the MagA‐F proteins. In this work, we employ isothermal calorimetry (ITC), analytical ultracentrifugation (AUC), and X‐ray crystallography to investigate the function of MagC and show that MagC associates with the macroglobulin complex and with the peptidoglycan (PG). However, the catalytic residues of MagC display an inactive conformation that could suggest that it binds to PG but does not degrade it. We hypothesize that MagC could serve as an anchor between the MagD macroglobulin and the PG and could provide stabilization and/or regulation for the entire complex.

Identification and classification of papain-like cysteine proteinases

“…DUF2272 (PF10030) representatives, mostly proteobacterial, may degrade plant cell wall for bacteria living in herbivores' rumen (PDB ID: 4EYZ ) ( 85 ) or function as peptidoglycan amidase secreted to the periplasmic space of a competitor (Tse1, PDB ID: 4F0V ) ( 42 , 93 ). Eventually, this group also includes two families of unknown function: inactive DUF1175 (PF06672) binding to peptidoglycan ( 94 ) and bacterial family of unknown function DUF1287 (PF06940).…”