FKBP-type peptidyl-prolyl cis-trans isomerase from thermophilic microalga, Scenedesmus sp.: molecular characterisation and demonstration of acquired salinity and thermotolerance in E. coli by recombinant expression

Abstract

A novel complementary DNA (cDNA) encoding temperature and salt stress-responsive FK506-binding protein 12 (FKBP12), a chaperone with peptidyl-prolyl cis-trans isomerase (PPIase) activity was isolated using suppression subtractive hybridization (SSH) technique from a thermophilic chlorophycean microalga, Scenedesmus sp., isolated from the Manikaran hot springs at Himachal Pradesh, India. To our best knowledge, this is the first report of temperature and salt-responsive FKBP12 isolated from a microalgae. The Scenedesmus FKBP12 (Sce.FKBP12) nucleotide sequence revealed the presence of an open reading frame of 327 bp, encoding 108 amino acid protein containing a single FKBP-like domain with a predicted molecular weight of 12 KDa. Amino acid sequence comparison of Sce.FKBP12 with its ortholog from other eukaryotic organisms showed structural conservation among each other. Expression profile of Sce.FKBP12 gene using quantitative real-time PCR showed significant up-regulated expression under temperature and salinity stress. The recombinant Sce.FKBP12 was over-expressed in Escherichia coli using pET28b expression vector. The recombinant expression of Sce.FKBP12 in E. coli cells imparted temperature and salinity tolerance to the host cells, implying a significant role of Sce.FKBP12 in stress tolerance mechanisms. Sce.FKBP12 could be a promising transgene candidate for imparting abiotic stress tolerance in crop plants, and they need to be further evaluated using plant models like Arabidopsis or Tobacco for confirming its potential as a transgene candidate in development of temperature and salinity-tolerant transgenic crops for improved and sustained productions in adverse agro-climatic conditions.