Crystal Structure Of C-terminal Domain Of Peptidyl-prolyl Cis-trans Isomerase (PPIase) From Pseudomonas Syringae Pv. Tomato Str. DC3000 (PSPTO DC3000) At 1.6? Resolution

The study of this paper is to insight the crystal structure of PSPTO-PPIase protein by structural biology.Using the bioinformatics analysis,PSPTO-PPIase,as a member of the FKBP subfamily in the super-family of the peptide prolyl isomerase(PPIase),has the activity of catalyzing the conversion between the cis and trans configurations ofprolinewhich trigger switching the backbone conformation of the target protein from cis to trans or trans to cis.And aPPIase of the FKBP subfamilybinds FK506 or rapmycin.The gene of the PSPTO-PPIase was cloned from the genome of Pseudomonas syringae pv.tomato str.DC3000,and expressed in E.coliby PHAT2 expression vector.The protein of PSPTO-PPIase was purifiedby affinity chromatography,ion exchange and exclusion chromatography.The purity was over 95%.And the protein was utilized to screen crystallizing conditionsand to optimize crystal quality.Finally,the crystal of the C-terminal portion of PSPTO-PPIase was diffracted and collected data by X-RAY,and the dimensional structure of the C-terminal portion of PSPTO-PPIase is resolved and the model is refined at 1.6?.Comparison with the structures of the homologues,PSPTO-PPIase exhibits a typical characteristic of the FKBP-C domain structure,especially in the hydrophobic active site which consists of the conserved residues.AndThe biochemical data for PSPTO-PPIase binding FK506 indicates that PSPTO-PPIase is indeed one member of the FKBP family.The loop4 is the significantly divergent region when superimposing the structural models of the homologues.The loop4 consisting of the successive small residue might has function for choosing the specific substrate.PSPTO-PPIase has much more similarity in dimensional structure with TcMIP,comparison to other homologues.Thereby we speculated that PSPTO-PPIase has the similar auxiliary virulence roles to the hosts with the TcMIP.FK506 and rapmycin inhibits the activity of the PSPTO-PPIase.The insight of PSPTO-PPIase structure at high resolution will be the base and provides clues for further exploring its virulence role in the pathogenesis of the Pseudomonas syringae pv.tomato str.DC3000.