Isolation, molecular characterisation and expression level of cytosolic heat-shock protein 90 (hsp90) genes of cryptocoryne ciliata, a halophyte plant

As sessile organisms, plants need osmotic adjustment and intercellular molecule changes for survival.Heat-shock proteins (HSPs)/ chaperones have been identified as the molecules involved in homeostasis and plays a crucial role in protecting plants against stresses.The HSPsproteins re-establish protein conformation through the folding, assembly, translocation degradation, stabilization of membrane protein (Wang et al., 2004;Wei et al., 2020).So far, more than twenty different family of HSPproteins that have chaperone activity have been discovered (Kosmaoglou et al., 2008).Five major HSPs/chaperones families have been classified according to their molecular weight, which are the small HSP family (12-40 KDa), HSP60 family (60 KDa), HSP70 family (70 KDa), HSP90 family (90 KDa), and HSP100 family (100 KDa) (Wang et al., 2004).HSP90 is one of the most abundant proteins expressed Abstract: Heat-shock protein 90 (HSP90) assembly in the cell involves protein-folding, as well as plant growth and response to environmental stimuli.Little is known regarding the sequence and function of HSP90s in halophytes plants.In the present study, a partial cDNA sequence of CcHsp90-1 and, a full-length cDNA of CcHsp90-2 from Cryptocoryne ciliata were cloned and sequenced.The full-length CcHsp90-2 cDNA sequence, containing 2465 base pairs, encoding a protein of 700 amino acids.The molecular mass of CcHsp90-2 protein was estimated at 79.95 kDa, which is 89 to 94 % homology to plant HSP90 protein.The protein possesses five-conserved amino acid signature sequence motifs characteristic of the HSP90 family and a C-terminus MEEVD penta-peptide characteristic, encoded by HSP90A group, which is mainly expressed in the cytosol.The predicted quaternary architecture structure for CcHsp90-2 protein generated through molecular modeling was globally akin to yeast HSP90.The CcHsp90s gene expression analyses in leaves of C. ciliata towards salinity treatment using the qRT-PCR analysis showed that both, CcHsp90-1 and CcHsp90-2 genes were significantly up-regulated with an optimum expression of 5.66 and 8.94-fold, respectively.It is suggested that few HSP90 isoforms might be synergistically exerted in regulating the salinity stress by C. ciliata.