Characterization of a 17kDa FKBP-type peptidyl-prolyl cis/trans isomerase from Vibrio anguillarum

Abstract

Peptidyl-prolyl cis/trans isomerase (PPIase) catalyzes the isomerization of peptide bonds for conformational changes in native folded protein. FKBP-type of PPIase was isolated from Vibrio anguillarum O1 and named as VaFKBP17. To investigate its biochemical properties, the ppi gene from V. anguillarum O1 was isolated and overexpressed in Escherichia coli. VaFKBP17, with about 17kDa molecular size, was performed protease-coupled assay for isomerization activity. Result indicated that activity of VaFKBP17 was the highest at low temperature (5°C) and alkaline conditions (pH 10) using Succinyl-Ala-Phe-Pro-Phe-pnitroanilide as substrate. With immunosuppressant FK506, isomerization activity of VaFKBP17 was inhibited. Through citrate synthase thermal aggregation activity, chaperon activity of VaFKBP17 was also checked. Based on its ability to catalyze refolding, effect on inclusion body was investigated during dilution process. As a result, VaFKBP17 showed the ability to assist protein refolding. The results provide evidence that VaFKBP17 possesses chaperone-like activity. We analyzed the structural homology modeling of VaFKBP17 comparison of bacterial FKBPs.