A Novel Antimicrobial Peptide Was Designed Based On The Mechanism Of Outer Membrane Protein Production

As an important part of the outer membrane of gram-negative escherichia coli,?-barrel outer membrane proteins(OMPs),play an important role in the life activities of bacteria,are involved in a variety of biological processes of bacteria,such as the uptake of nutrients and the excretion of metabolic wastes,the adhesion of bacteria and immune escape.However,the formation of OMPs is a very complex process.The new peptide chain needs to pass through the inner membrane,cross the hydrophilic periplasmic without energy,and then insert the outer membrane.In the whole process,it needs the assistance of a variety of cytokines and quality control factors.In this study,a novel antimicrobial peptide was designed and developed according to the transport process of the new peptide chain OMPs in the periplasmic.In this study,a series of c-terminal truncated mutant plasmids of OmpF were firstly constructed,and many antimicrobial peptides which can affect the integrity of outer membrane were selected by the method of expression of various proteins in bacteria.Furthermore,we selected the shortest sequence of ompf-7 for chemical synthesis in vitro,and introduced the polypeptide into bacterial cells under the condition of EDTA assistance to detect the bactericidal activity of the polypeptide.The results showed that the polypeptide ompf-7 had good antibacterial activity against logarithmic Escherichia coli.In addition,this study explored the bactericidal mechanism of peptides by chemical cross-linking and photo-crosslinking in living cells.It was proved that the polypeptide OmpF-7 can interact with both molecular chaperone SurA and Skp.By systematically studying the interaction between peptides and SurA,this study further found that peptide OmpF-7 can interfere with the interaction of SurA with normal outer membrane proteins and the formation of SurA dimers.We speculate that after the introduction of polypeptide ompf-7 into bacterial cells,it interferes with the functions of SurA and Skp at the same time,causing bacteria to exhibit the phenotype of double knockout of Skp and SurA genesIn order to facilitate future applications,we added a cell membrane permeable that can pass through the outer membrane of the bacteria at the N-terminus of OmpF-7,so that the peptide can directly enter the bacterial cell without the aid of EDTA.We have identified the antibacterial activity of CMP-OmpF-7 in vitro.Studies have shown that the polypeptide CMP-OmpF-7 can effectively kill E.coli,Pseudomonas aeruginosa,Klebsiella pneumoniae and Acinetobacter baumannii It has no bactericidal effect on Salmonella and Shigella.