Heterologous expression of a salinity and developmentally regulated rice cyclophilin gene (OsCyp2) in E. coli and S. cerevisiae confers tolerance towards multiple abiotic stresses.

Cyclophilin 2 (OsCyp2) is a cytosolic member of immunophilin family from rice. We have isolated its full length cDNA (1,056 bp) with an open reading frame of 519 bp encoding a polypeptide of 172 amino acids and an estimated pI of 8.61. Peptidyl prolyl cis-trans isomerase activity of the protein was determined using N-succinyl-ala-ala-pro-phe-p-nitroanilidine as peptide substrate. It has a catalytic efficiency (K (cat)/K (m)) of 4.5 x 10(6)/(mol/l)/s, which is comparable to known cyclophilins from plants. Its activity is specifically inhibited by cyclosporin A, a macrolide drug inhibitor of cyclophilins. Transcript analysis showed it to be a developmentally and differentially regulated gene; showing changes in abundance at seedling, tillering and heading stage under non-stress and salinity stress conditions. Expression of OsCyp2 enhances the ability of Escherichia coli to survive under diverse abiotic stresses viz. salinity, high temperature, osmotic stress (mannitol) and oxidative stress (H(2)O(2)). OsCyp2 was able to complement the yeast mutant lacking native Cyp2 and also improved the growth of wild type yeast under above-mentioned stress conditions. Based on these results, we propose that OsCyp2 may serve as a 'suitable candidate' for raising transgenic plants for enhanced multiple abiotic stress tolerance.