A cyclophilin from Griffithsia japonica has thermoprotective activity and is affected by CsA |
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Authors: | Cho Eun Kyung Lee Yoo Kyung Hong Choo Bong |
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Institution: | Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Korea. choeun@snu.ac.kr |
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Abstract: | Members of the multifunctional Cyp family have been isolated from a wide range of organisms. However, few functional studies have been performed on the role of these proteins as chaperones in red alga. For studying the function of cDNA GjCyp-1 isolated from the red alga (Griffithsia japonica), we expressed and purified a recombinant GjCyp-1 containing a hexahistidine tag at the amino-terminus in Escherichia coli. An expressed fusion protein, H6GjCyp-1 maintained the stability of E. coli proteins up to 50 degrees C. For a functional bioassay for recombinant H6GjCyp-1, the viability of E. coli cells overexpressing H6GjCyp-1 was compared with that of cells not expressing H6GjCyp-1 at 50 degrees C. After high temperature treatment for 1 h, E. coli overexpressing H6GjCyp-1 survived about three times longer than E. coli lacking H6GjCyp-1. Measurement of the light scattering of luciferase (luc) showed that GjCyp-1 prevents the aggregation of luc during mild heat stress and that the thermoprotective activity of GjCyp-1 is blocked by cyclosporin A (CsA), an inhibitor of Cyps. Furthermore, the Cyp-CsA complex inhibited the growth of E. coli under normal conditions. The results of the GjCyp-1 bioassays as well as in vitro studies strongly suggest that Cyp confers thermotolerance to E. coli. |
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