No abstract

Lytic transglycosylases are abundant peptidoglycan lysing enzymes that degrade the heteropolymers of bacterial cell walls in metabolic processes or in the course of a bacteriophage infection. The conventional catalytic mechanism of transglycosylases involves only the Glu or Asp residue. Endolysin gp144 of Pseudomonas aeruginosa bacteriophage phiKZ belongs to the family of Gram-negative transglycosylases with a modular composition and C-terminal location of the catalytic domain. Glu115 of gp144 performs the predicted role of a catalytic residue. However, replacement of this residue does not completely eliminate the activity of the mutant protein. Site-directed mutagenesis has revealed the participation of Tyr197 in the catalytic mechanism, as well as the presence of a second active site involving Glu178 and Tyr147. The existence of the dual active site was supported by computer modeling and monitoring of the molecular dynamics of the changes in the conformation and surface charge distribution as a consequence of point mutations.

No abstract

Currently, the bacterial etiology infectious diseases still remain a global health problem. Most of them are caused by gram-negative pathogenic microorganisms. The traditional method of infectious diseases treatment is based on the use of antibiotics. However, the rapid development of the resistance of pathogenic microorganisms to existing antibiotics forces to seek alternatives to traditional therapy. One of such alternatives is the therapy with bacteriophage endolysins - bacteriolytic enzymes capable of destroying the bacterial cell wall by hydrolyzing the peptidoglycan. Endolysins are highly specific for certain pathogens. The main limitation of their use towards gram- negative bacteria is the presence of an outer membrane in the latter preventing the penetration of lytic enzyme to its substrate. The effectiveness of endolysin penetration can be increased by destabilizing the outer membrane of gram-negative bacteria