| The traditional antibiotics non-selectively disturb intestinal flora,causing side effects;now available antibiotics or antimicrobial candidates are used to kill bacteria or inhibit the growth of bacteria by inhibiting targets,triggering drug-resistance in response.At present,the dilemma of antimicrobial infections is more and more drugresistant bacteria isolated from clinic,while the number of new types of antibiotics on the market is on the decrease.In order to alleviate the problem of antibiotic resistance,on the one hand,it is desiderate to explore the feasibility of non-antibiotic effect(no killing and no inhibiting)to control pathogen infection;on the other hand,it is urgent to launch research on new types of antibiotics,especially based on new targets and new mechanisms.Pathogenic bacteria exert their virulence(the ability to infect host)by the virulence factors;virulence-related genes are the decisive factors of infection,but not necessary for the growth and survival of the pathogen.Therefore,it can be as a complementary strategy for the study of small-molecule intervention on pathogenic bacteria.Caseinolytic protease P,ClpP,is one of the housekeeping proteins regulating the pathogenicity in Staphylococcus aureus.ClpP proteolytic activity can be inhibited by ?-lactones,which weaken the production of virulence factors,and control pathogen infection by non-antibiotic effects,but there is no rigorous conceptual validation studies in the literature.On the other hand,the natural product,ADEPs,can activate ClpP and transform it into an uncontrollable proteolytic enzyme,leading to ClpP dysfunction and degradation of the substrate proteins falsely,so as to achieving antimicrobial.This strategy based on stimulating bacterial targets function is different from the existing mechanism by inhibiting.However,the selectivity intervention between bacterial ClpP and mitochondrial ClpP has been unsolved.This paper focuses on the study of small-molecule intervention on Staphylococcus aureus ClpP(SaClpP)function and new types of antimicrobial agents.Some inhibitors have been obtained by a high-throughput screen with about 2000 compounds from drugs on the market and preclinical candidates,which can effectively inhibit the interaction between SaClpX and SaClpP,compound 29307 targeted SaClpP,affecting the protein thermal stability.Meanwhile,with a highthroughput screen about 2000 compounds from drugs on the market and preclinical candidates and about 100 compounds synthesized and optimized by the cooperative research group,I found that DAs compounds activate SaClpP to degrade the cell division protein FtsZ,and their antimicrobial activities are closely related to SaClpP and show an anti-persisters effect.At the same time,I also found a compound MWP446,whose antimicrobial activity was related to the abundance of SaClpP,however,the enzyme activity of SaClpP was not affected by MWP446 at the molecular level.There are a mutation of ClpPG69 R in the mutant strain,so the preliminary target identification study was conducted.In addition,I have evaluated the antibacterial activity of tetrahydrocarbazole compounds,which were designed and synthesized by the collaborators.Through MIC assay and preliminary safety evaluation,the tetrahydrocarbazole derivatives with new skeleton structure were verified to be antibacterial compounds,but the mechanism of action is still unclear.These compounds showed good antibacterial activity against Staphylococcus aureus,clinical drug-resistant bacteria and Escherichia coli AB1157,establishing a foundation for further studies on new broad-spectrum antibacterial agents.In conclusion,the study of small molecule regulators targeting SaClpP and the evaluation of antibacterial activity of new compounds were carried out in this paper.It provides a small molecule tool for chemical intervention of SaClpP and further confirms that ClpP can be used as a new antibacterial target.It also provides a new chemical skeleton for new types of broad-spectrum antibiotics. |
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