Study On The Interaction Between SpA Protein Of Staphylococcus Aureus And Heparin

Heparin is a widely used anticoagulant drug in clinical practice and can be used to modify the surface of medical devices to improve their blood compatibility.Staphylococcus aureus,the main pathogen of humans and animals,adheres to the heparin coating and usually causes catheter-related blood infections.Studies have shown that heparin binds to S.aureus surface localization proteins and promotes the formation and infection of S.aureus organisms.However,the mechanism of interaction between heparin and S.aureus surface protein still needs further study.Therefore,understanding the mechanism of interaction between heparin and S.aureus surface protein will help to understand the interaction between the host and the microorganism and the mechanism of S.aureus infection,and provide a certain theoretical basis for health and safety testing and auxiliary clinical treatment.We chose S.aureus NCTC8325(WT)as the experimental strain.During the experiment,we separated and purified S.aureus protein A(Sp A)through a heparin agarose chromatography column and found that Sp A of S.aureus NCTC8325 is a heparin-binding protein,which helps S.aureus NCTC8325 and heparin Interaction.The cell wall anchored Sp A is one of the most important virulence factors of S.aureus,which has a lysin-like motif(Lys M).We constructed the plasmid p ET15b-spa and purified the Sp A protein;using the plasmid p ET15b-spa as a template to construct the plasmid p ET15b-spa-mutant and purified the Sp A(G385 ·)protein with the Lys M domain removed;the Sp A and Sp A(G385 ·)Incubation with fluorescently labeled heparin showed that the binding ability of Sp A(G385 ·)to heparin was reduced by 50% compared to Sp A,indicating that the Lys M domain contributes to the binding of Sp A to heparin.In addition,we incubate the WT and ?spa :: Em strains with heparin,and the results show that WT binds 1.3 times more heparin than the ?spa :: Em strain,which shows that the knockout of the spa gene reduces the ability of the bacteria to bind heparin.Taken together,these results indicate that the Sp A protein promotes the interaction between S.aureus NCTC8325 and heparin through the Lys M domain.In addition,two other surfacelocated heparin-binding proteins,Map and Hlg A,of S.aureus NCTC8325 were identified.