Title: Phage lytic enzymes targeting streptococci Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2014
Publication Date: N/A
Technical Abstract: Streptococcal pathogens contribute to a wide variety of human and livestock diseases. There is a need for new antimicrobials to replace over-used conventional antibiotics. Bacteriophage (viruses that infect bacteria) endolysins (enzymes that help degrade the bacterial cell wall) are ideal candidate novel antimicrobials. The Streptococcus agalactiae bacteriophage B30 endolysin contains three domains: cysteine, histidine-dependent amidohydrolase/peptidase (CHAP), Acm glycosidase, and the SH3b cell wall binding domain. Truncations and point mutations indicated that the Acm domain requires the SH3b domain for activity, while the CHAP domain is responsible for nearly all the cell lysis activity. Similarly, the LambdaSa2 prophage endolysin gene isolated from a Group B streptococcal genome was shown, by homology screening and biochemical analysis, to harbor an amidase-5 (endopeptidase) domain, an amidase-4 (glycosidase) domain and two Cpl-7 cell wall-binding domains. Turbidity reduction and plate lysis assays indicate that this hydrolase shows strong lytic activity toward numerous streptococcal pathogens. Deletion analysis indicates that the N-terminal endopeptidase domain with both Cpl-7 domains can lyse with a higher specific activity than the full length protein (against some strains). The truncated constructs harboring the glycosidase domain are virtually inactive, showing only minimal activity on plate lysis assays. Thus, two candidate endolysin domains, each with unique cut sites in the bacterial cell wall, hold promise in developing novel antimicrobials that are refractory to resistance development.