The Interaction Between Mycobacterium Tuberculosis Fatty Acyl-CoA Synthetase FadD13 And Macrophage

Mycobacterium tuberculosis(Mtb)is an intracellular pathogen of tuberculosis,and macrophages are the main host cells in human body for Mtb.Protein-protein interaction between Mtb and host cell plays an important role in infection and immunity.In this study,we used the Mtb protein chip,interacting with macrophage lysates which stimulated by virulent strain H37 Rv and attenuated strain H37 Ra respectively,screened 283 Mtb differential proteins.These proteins may be virulence related.Bioinformatics analysis was used to analysis the function of the screened differential proteins.The results show that these proteins were mainly gathered in cell wall related proteins,and for the metabolic pathway,the differential proteins mainly associated with synthesis of secondary metabolites,amino acid biosynthesis and purine metabolism.In this study,five secreted proteins were selected for preliminary functional studies.The resuts show that FadD13 overexpressed in M.smegmatis could induce the bacteria agglutination.Flow cytometry and plate counting results show that the phagocytosis of FadD13 overexpression M.smegmatis strain by macrophages was reduced.Mycobacterium agglutination has a great influence on the phagocytosis of Mtb by macrophages and the maturation of phagosome.FadD13 may affect the virulence of Mtb by regulating its agglutination.Mtb FadD13 is related to the synthesis of mycolic acid,so it is an attractive drug target,but its role during Mtb infection remains unclear.In this study,we systematically investigated the function of FadD13.We found that FadD13 could promote the production of proinflammatory cytokines IL-1?,IL-18 and IL-6.Bimolecular fluorescence complementation and colocalization showed that the binding partner of FadD13 in macrophage was eEF1A1(a eukaryotic translation elongation factor),and this binding may inhibit eEF1A1 degradation in macrophage.Knockdown eEF1A1 expression in macrophage abrogated the function of FadD13 during H37 Rv infection.In addition,?fadD13 mutant decreased the expression of the NF-?B signaling pathway-related proteins p50 and p65 in macrophage,so did the eEF1A1 knockdown macrophage infected with H37 Rv.Taken together,FadD13 regulates proinflammatory cytokines secretion dependent on the NF-?B signaling pathway by binding to eEF1A1 during Mtb infection.Thereby,Mtb FadD13 is crucial for Mtb infection and immune process.In addition,deletion of FadD13 in H37 Rv reduced Mtb survival in macrophages during Mtb infection.And FadD13 protein could induce macrophage LDH release and decrease cell viability.FM1-43 staining images show that FadD13 could make the cell membrane broken.Therefore,FadD13 plays a virulent role in proliferation in macrophages during Mtb infection.Taken together,the screened 283 differential proteins provided important reference for systematicly studying the interaction between Mtb and macrophages.In this research,we have conducted in-depth study on the function of FadD13 during Mtb infection,which provided a theoretical basis for the infection mechanism of Mtb and the development of anti-tuberculosis drugs.