ENHANCED STAPHYLOLYTIC ACTIVITY OF THE STAPHYLOCOCCUS AUREUS BACTERIOPHAGE VB_SAUS-PHILPLA88 VIRION-ASSOCIATED PEPTIDOGLYCAN HYDROLASE HYDH5: FUSIONS, DELETIONS AND SYNERGY WITH LYSH5

摘要

Virion-associated peptidoglycan-hydrolases are potential antimicrobials due to their ability to lyse Gram-positive bacteria on contact. Full-length HydH5, a virion- associated peptidoglycan-hydrolase from the Staphylococcus aureus bacteriophage vB_SauS-phi-IPLA88, and two truncated derivatives, containing only the CHAP domain, exhibited high lytic activity against live S. aureus cells. Three different fusion proteins were created: HydH5 peptidoglycan hydrolase-lysostaphin, HydH5 peptidoglycan hydrolase-SH3b, or HydH5CHAP-SH3b. Each recombinant fusion polypeptide showed higher staphylolytic activity than the parental enzyme or its deletion construct. Both parental and fusion proteins lysed S. aureus cells in zymograms, plate-lysis and turbidity-reduction assays. In plate-lysis assays, HydH5 and its derivatives lysed bovine and human S. aureus, S. aureus MRSA N315 strain, and human Staphylococcus epidermidis strains. Several non-staphylococcal bacteria were not affected. HydH5 and its derivatives displayed antimicrobial synergy with the endolysin LysH5 in vitro, suggesting distinct cut sites for the two enzymes, which combined are potentially more efficient for eliminating staphylococcal infections.