Muralytic activity and modular structure of the endolysins of Pseudomonas aeruginosa bacteriophages phi KZ and EL

作者：Briers Yves^*; Volckaert Guido; Cornelissen Anneleen; Lagaert Stijn; Michiels Chris W; Hertveldt Kirsten; Lavigne Rob

来源：Molecular Microbiology, 2007, 65(5): 1334-1344.

DOI：10.1111/j.1365-2958.2007.05870.x

Pseudomonas aeruginosa bacteriophage endolysins KZ144 (phage phi KZ) 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 pepticloglycan 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.

• 出版日期2007-9