A Novel Chimeric Endolysin with Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus

Abstract

Cysteine/histidine-dependent amidohydrolase/peptidase (CHAP) and amidase are known as catalytic domains of the bacteriophage-derived endolysin LysK and were previously reported to show lytic activity against methicillin-resistant Staphylococcus aureus (MRSA). In the current study, the in silico design and analysis of chimeric CHAP-amidase model was applied to enhance the stability and solubility of protein, which was achieved through improving the properties of primary, secondary and tertiary structures. The coding gene sequence of the chimeric CHAP-amidase was synthesized and subcloned into the pET-22(+) expression vector, and the recombinant protein was expressed in E. coli BL21 (DE3) strain. Subsequent affinity-based purification yielded ~12 mg soluble protein per liter of E. coli culture. Statistical analysis indicated that concentrations of ≥1 μg/mL of the purified protein have significant antibacterial activity against S. aureus MRSA252 cells. The engineered chimeric CHAP-amidase exhibited 3.2 log reduction of MRSA252 cell counts at the concentration of 10 μg/mL. A synergistic interaction between CHAP-amidase and vancomycin was detected by using checkerboard assay and calculating the fractional inhibitory concentration (FIC) index. This synergistic effect was shown by 8-fold reduction in the minimum inhibitory concentration of vancomycin. The chimeric CHAP-amidase displayed strong antibacterial activity against S. aureus, S. epidermidis, and enterococcus. However, it did not indicate any significant antibacterial activity against E. coli and Lactococcus lactis. Taken together, these findings suggest that our chimeric CHAP-amidase might represent potential to be used for the development of efficient antibacterial therapies targeting MRSA and certain Gram-positive bacteria.

Therapeutics and delivery vehicles for local treatment of osteomyelitis

“…78 Furthermore, this chimeric enzyme exerted synergistic effects with vancomycin. 78 As with other previously mentioned therapeutics, host enzymes are not stable in vivo and thus must be applied locally for optimal efficacy.…”

“…49,77 A recent focus has been on chimeric endolysins, which may enhance the bactericidal potential of these enzymes. [78][79][80] One recently engineered chimeric endolysin exerted bactericidal efficacy on S. aureus, S. epidermidis, and enterococci, which is promising for polymicrobial osteomyelitis infection treatment. 78 Furthermore, this chimeric enzyme exerted synergistic effects with vancomycin.…”

“…[78][79][80] One recently engineered chimeric endolysin exerted bactericidal efficacy on S. aureus, S. epidermidis, and enterococci, which is promising for polymicrobial osteomyelitis infection treatment. 78 Furthermore, this chimeric enzyme exerted synergistic effects with vancomycin. 78 As with other previously mentioned therapeutics, host enzymes are not stable in vivo and thus must be applied locally for optimal efficacy.…”

Recombinant Endolysins as Potential Therapeutics against Antibiotic-Resistant Staphylococcus aureus: Current Status of Research and Novel Delivery Strategies

“…Finally, to enhance their therapeutic activity and to avoid the development of resistance, multiple endolysins may be used in combination with antibiotics to treat bacterial infections (1,100). Synergistic effects among endolysins and between endolysins and other antimicrobial agents have been reported (101)(102)(103). Other topics related to the systemic application of endolysins, such as immunogenicity, toxicity, and serum half-life, have been discussed elsewhere (65) and are not a focus of this review.…”

The dawn of phage therapy

“…( b ) Endolysin is another useful phage protein that can fragment the host bacterial cell wall resulting in bacterial cell death. Phage‐encoded endolysins have been isolated and used against Bacillus anthracis using lysin PlyPH and PlyG, Acinetobacter baumannii using lysin PlyF307, S. aureus using phage lysin LysGH15 and Ply187, and Staphylococcus epidermidis , S. aureus , and Enterococcus using LysK . A broad‐spectrum phage–derived lysin ABgp46 lyses Salmonella typhimurium , P. aeruginosa , and MDR A. baumannii .…”