A Highly Active Chimeric Lysin with a Calcium-Enhanced Bactericidal Activity against Staphylococcus aureus In Vitro and In Vivo

Abstract

Lysins, including chimeric lysins, have recently been explored as novel promising alternatives to failing antibiotics in treating multi-drug resistant (MDR) pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Herein, by fusing the CHAP (cysteine, histidine-dependent amidohydrolase/peptidase) catalytic domain from the Ply187 lysin with the non-SH3b cell-wall binding domain from the LysSA97 lysin, a new chimeric lysin ClyC was constructed with Ca2+-enhanced bactericidal activity against all S. aureus strains tested, including MRSA. Notably, treating S. aureus with 50 μg/mL of ClyC in the presence of 100 μM Ca2+ lead to a reduction of 9 Log10 (CFU/mL) in viable bacterial number, which was the first time to observe a lysin showing such a high activity. In addition, the effective concentration of ClyC could be decreased dramatically from 12 to 1 μg/mL by combination with 0.3 μg/mL of penicillin G. In a mouse model of S. aureus bacteremia, a single intraperitoneal administration of 0.1 mg/mouse of ClyC significantly improved the survival rates and reduced 2 Log10 (CFU/mL) of the bacterial burdens in the organs of the infected mice. ClyC was also found stable after lyophilization without cryoprotectants. Based on the above observations, ClyC could be a promising candidate against S. aureus infections.

Smart Chimeric Lysin ClyC Loaded Alginate Hydrogel Reduces Staphylococcus aureus Induced Bone Infection

“…Researchers had demonstrated a synergetic approach to bacterial treatment by a combination of endolysin and antibiotics (Daniel et al, 2010;Letrado et al, 2018). In our previous studies, we showed that penicillin G and ClyC had a synergistic effect, reducing the MIC of ClyC for planktonic and sessile S. aureus (Li et al, 2021). It was beneficial to reduce the working concentration of ClyC in the lesion and weaken potential safety hazards.…”

“…The chimeric lysin, ClyC, was expressed as described previously (Li et al, 2021). Concentration of ClyC was determined by BCA assay and visualized by SDS-PAGE.…”

“…ClyC, a novel chimeric lysin, has specificity and robust killing efficacy against drug-resistant and susceptible S. aureus and other staphylococcal, the effect of which could be further enhanced with calcium. Also, ClyC protected mice from lethal systemic S. aureus infection (Li et al, 2021). However, the effect of endolysins are limited by its instability and short half-life in vivo, as well as the cytotoxicity tested in vitro (Resch et al, 2011;Seijsing et al, 2018).…”

In-situ and Real-Time Monitoring of the Interaction Between Lysins and Staphylococcus aureus Biofilm by Surface Plasmon Resonance

“…The plasmid constructs and protein purification procedures were performed as in our previous studies ( Huang et al, 2015 ; Yang et al, 2017 ; Li et al, 2021 ). Briefly, E. coli BL21(DE3) cells with their plasmids were grown in LB medium supplemented with 50 μg/mL kanamycin at 37°C 160 rpm to an OD600 of 0.4∼0.6.…”

“…For example, by fusing the CD of lysin Ply187 with the CBD of PlySs2, a novel chimeric lysin, ClyF, with increased thermostability, pH tolerance, and antibacterial activity against both planktonic and biofilm MRSA was formed ( Yang et al, 2017 ). Similarly, ClyC, a novel chimeric lysin with increased bactericidal activity against S. aureus strains and its biofilms, including MRSA, in the presence of calcium ions was formed by fusing the CD of lysin Ply187 with the CBD of LysSA97 ( Li et al, 2021 ). Despite the successful engineering of chimeric lysis, questions still remain such as how the lysins interact with the biofilms and if different CDs and CBDs could affect the ability of lysins to remove biofilms.…”