|YOUNG, CARLY - Ashland-Us|
|FRANKS, ASHLEY - Ashland-Us|
|HYMAN, PAUL - Ashland-Us|
Submitted to: FEMS Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2016
Publication Date: 9/14/2016
Citation: Swift, S., Rowley, D.T., Young, C., Franks, A., Hyman, P., Donovan, D.M. 2016. Characterization of the endolysin from the Enterococcus faecalis bacteriophage VD13. FEMS Microbiology Letters. doi: 10.1093/femsle/fnw216.
Interpretive Summary: There is a need for novel antimicrobials that are refractory to resistance development. Viruses that infect bacteria (bacteriophage; phage) have co-evolved with their host and thus their phage lytic proteins (endolysins) are highly refractory to resistance development. This work describes the isolation, purification and testing of the VD13 entorococcal phage endolysin for lytic activity and thermostability. It is lytic for multiple strains of Enterococcus faecalis, but not for other species tested. It demonstrates an unusual phenomena wherein the activity increases upon heating in certain buffers. This finding although the mechanism is not fully explained might lead to a novel alternative for long term storage and increased thermostability for use in underpriveledged countries where refrigeration is lacking or on the farm where longer shelf-life is desireable.
Technical Abstract: Bacteriophage infecting bacteria produce endolysins (peptidoglycan hydrolases) to lyse the host cell from within and release nascent bacteriophage particles. Recombinant endolysins can also lyse Gram-positive bacteria when added exogenously. As a potential alternative to antibiotics, we cloned and expressed the enterococcal VD13 bacteriophage endolysin. VD13 endolysin has a CHAP catalytic domain with 92% identity by amino acid sequence with the bacteriophage IME-EF1 endolysin. The predicted size of VD13 endolysin is 27 kDa and the size was verified by SDS-PAGE. The VD13 endolysin was capable of lysing strains of its host, Enterococcus faecalis, but not Enterococcus faecium or other non-enterococci bacteria tested. VD13 endolysin had activity from pH 4 to pH 8, with peak activity at pH 5, and exhibited greater activity in the presence of calcium ions. Optimum activity at pH 5 occurred in the absence of NaCl. VD13 endolysin, in ammonium acetate calcium chloride buffer pH 5, was stimulated to higher activity upon heating at temperatures up to 65 °C for 30 minutes, whereas activity was lost upon heating to 42 °C, in pH 7 buffer.