Exploring The Interaction Between The Master Transcription Factor FlhD-FlhC Complex Of Salmonella Flagellar System And Transcriptional Regulatory Elements

Bacteria use flagella to move towards environments that are favorable for their survival and to compete with other microorganisms.In addition to their motility function,these complex organelles play important roles in substrate adhesion,biofilm formation,and host cell invasion,making the flagellar synthesis pathway one of the important targets for designing new antibacterial drugs.Flagella are complex organelles composed of a series of protein components that form a nanomolecular machine.According to the order of transcription,The related genes expressing flagellar proteins are divided into three levels,The flhDC operon is located in the first level,and its gene expression product FlhD₄C₂ complex is a necessary transcriptional activator for downstream flagellar gene expression.Therefore,the flhDC operon is the most crucial site for regulating bacterial flagellar synthesis and assembly,and its regulation involves three levels:DNA,RNA,and protein levels.The proteins studied in this paper,YdiV,FliT,DnaK,and YhjK,are reported in the literature to regulate the function of the FlhD-FlhC complex at the protein level.This paper investigates the key transcriptional activator FlhD-FlhC complex in the flagellar synthesis and assembly process in Salmonella,and explores the regulatory mechanisms of YdiV,FliT,DnaK,and YhjK on its function.The composition ratio and thermal stability of the FlhD-FlhC complex were determined by multiple-angle light scattering and thermal denaturation experiments.The interactions between the proteins YdiV,FliT,and DnaK and the FlhD-FlhC complex were verified by in vitro experiments,and ternary YdiV-FlhD-FlhC,DnaK-FlhD-FlhC,and quaternary YdiV-FlhD-FlhC-FliT complexes were constructed.The structure of the complex was preliminarily characterized by negative staining technology,laying the theoretical foundation for using structural biology methods to elucidate the regulatory mechanism.These research results have important guiding significance for designing new antibacterial drugs and preventing and treating bacterial infections.