Display of aggregation-prone ligand binding domain of human PPAR gamma on surface of bacteriophage lambda

<正> Aim:To display the aggregation-prone ligand binding domain (LBD) of the hu-man peroxisome proliferator-activated receptor gamma (PPARγ) on the surface ofbacteriophages to establish an easy screening assay for the identification of PPARγligands.Methods:Plasmids were constructed for the expression of the PPARγLBD as a fusion to the N-terminus of the g3p protein of filamentous phage or theC-terminus of the capsid protein D (pD) of phage lambda.The fusion proteinswere expressed in E coli and solubility characteristics were compared.Polyclonalantibodies against the LBD as well as the pD protein were prepared for Westernblot analysis and phage capture assay.Results:The pD-LBD fusion protein waspartially soluble,whereas the LBD-g3p fusion protein was detected only in theinsoluble fraction.The pD-LBD fusion protein was efficiently incorporated inphage particles.Furthermore,the LBD was shown to be displayed on the surfaceof bacteriophage lambda.On average,the pD-LBD fusion protein accounted for28% of the total pD protein in the lambda head capsid.Conclusion:The hydro-phobic PPARγ LBD was expressed as a soluble form of fusion protein in E coli anddisplayed on the surface of bacteriophage lambda when it was fused to the lambdapD protein.The lambda pD fusion system could be used for improving the solu-bility of proteins that tend to form inclusion bodies when expressed in E coli.Thelambda phage particles displaying the LBD of PPARy may be of great value for theidentification of novel PPARγ ligands.