The Effects Of Different Chaperone Activities On The Folding Of Nascent Chains

Trigger Factor(TF)is a molecular chaperone with a ribosome-binding site in E.coli.As the first molecular chaperone encountered by nascent peptide chains after synthesis,it plays an important role in the molecular chaperone network of prokaryotes by performing the important function of assisting protein to fold correctly.The different domains of TF do not function completely independently,but cooperate with each other.TF has three molecular chaperone activities of foldase,unfoldase and holdase,which act on the nascent peptide chains to help the latter to fold.The purpose of this study is to explore the effects of the molecular chaperone activities on the folding of the nascent peptide chains by constructing ribosome-binding molecular chaperones with different chaperone activities.In this study,four molecular chaperones with different activities,Dna K,Clp B,Dna J and Skp,were selected as the targets for modification.The N domain of TF was fused to these four molecular chaperones to construct ribosome-binding fusion proteins of NTF-Dna K,NTF-Clp B,NTF-Dna J and NTF-Skp with different molecular chaperone activities.After expression and purification of these fusion proteins,the molecular chaperone activities and structural properties of the fusion proteins were investigated.The results showed that the presence of the N domain of TF did not affect the activities of the prepared fusion proteins.At the same time,the transcriptome,proteome,and phenotype data of single gene knock-out strains of TF and other molecular chaperones were also analyzed.It was found that the deletion of TF with multi-molecular chaperone activities could cause significant changes in the expression level of many genes,and finally resulted in a variety of changes in cellular physiology and phenotype.The effects of Dna K with foldase activity,Clp B with unfoldase activity and Skp with holdase activity on gene expression and cell phenotype were overlapped with those of TF.The results of this study will be helpful to further explain the effect of different molecular chaperone activities on protein folding,and lay the foundation for determining the physiological function of ribosome-binding molecular chaperones with different molecular chaperone activities.