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Muralytic activity and modular structure of the endolysins of Pseudomonas aeruginosa bacteriophages φKZ and EL
Author(s) -
Briers Yves,
Volckaert Guido,
Cornelissen Anneleen,
Lagaert Stijn,
Michiels Chris W.,
Hertveldt Kirsten,
Lavigne Rob
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05870.x
Subject(s) - peptidoglycan , lysin , biology , bacteriophage , bacillus subtilis , lytic cycle , biochemistry , bacterial cell structure , bacterial outer membrane , cell envelope , microbiology and biotechnology , bacteria , cell wall , escherichia coli , genetics , gene , virus
Summary Pseudomonas aeruginosa bacteriophage endolysins KZ144 (phage φKZ) and EL188 (phage EL) are highly lytic peptidoglycan hydrolases (210 000 and 390 000 units mg −1 ), active on a broad range of outer membrane‐permeabilized Gram‐negative species. Site‐directed mutagenesis indicates E115 (KZ144) and E155 (EL188) as their respective essential catalytic residues. Remarkably, both endolysins have a modular structure consisting of an N‐terminal substrate‐binding domain and a predicted C‐terminal catalytic module, a property previously only demonstrated in endolysins originating from phages infecting Gram‐positives and only in an inverse arrangement. Both binding domains contain conserved repeat sequences, consistent with those of some peptidoglycan hydrolases of Gram‐positive bacteria. Fusions of these domains with green fluorescent protein immediately label all outer membrane‐permeabilized Gram‐negative bacteria tested, isolated P. aeruginosa peptidoglycan and N‐acetylated Bacillus subtilis peptidoglycan, demonstrating the broad range of peptidoglycan‐binding capacity by these domains. Specifically, A1 chemotype peptidoglycan and fully N‐acetylated glucosamine units are essential for binding. Both KZ144 and EL188 appear to be a natural chimeric enzyme, originating from a recombination of a cell wall‐binding domain encoded by a Bacillus or Clostridium species and a catalytic domain of an unknown ancestor.