Crystal structure of the engineered endolysin mtEC340M.

Endolysins produced by bacteriophages play essential roles in the release of phage progeny by degrading the peptidoglycan layers of the bacterial cell wall. Bacteriophage-encoded endolysins have emerged as a new class of antibacterial agents to combat surging antibiotic resistance. The crystal structure of mtEC340M, an engineered endolysin EC340 from the PBEC131 phage that infects Escherichia coli, was determined.

Structural changes of antitoxin HigA from Shigella flexneri by binding of its cognate toxin HigB.

In toxin-antitoxin systems, many antitoxin proteins that neutralize their cognate toxin proteins also bind to DNA to repress transcription, and the DNA-binding affinity of the antitoxin is affected by its toxin. We solved crystal structures of the antitoxin HigA (apo-HigA) and its complex with the toxin HigB (HigBA) from Shigella flexneri. The apo-HigA shows a distinctive V-shaped homodimeric conformation with sequestered N-domains having a novel fold.