Abstract
Molecular chaperones (Hsps) have been shown to facilitate protein folding or assembly under various developmental and adverse environmental conditions. The aim of this study was to unravel a possible role of heat-shock proteins in conferring abiotic stress tolerance to plants. We isolated a cDNA encoding a cytoplasmic Hsp70 (PgHsc70) from Pennisetum glaucum by screening heat-stress cDNA library. PgHsc70 cDNA encoding 649 amino acids represents all conserved signature motifs characteristic of Hsp70s. The predicted molecular model of PgHsc70 protein suggests that the N-terminus ATP-binding region is evolutionarily conserved, in comparison to C-terminus peptide-binding domains. A single intron in ATPase domain coding region of PgHsc70 exhibited a high degree of conservation with respect to its position and phasing among other plant Hsp70 genes. Recombinant PgHsc70 protein purified from E. coli possessed in vitro chaperone activity and protected PgHsc70 expressing bacteria from damage caused by heat and salinity stress. Nucleotide sequence analysis of 5′ flanking promoter region of PgHsc70 gene revealed a potential heat-shock element (HSE) and other putative stress-responsive transcription factor binding sites. Positive correlation existed between differentially up-regulated PgHsc70 transcript levels and the duration and intensity of different environmental stresses. Molecular and biochemical analyses revealed that PgHsc70 gene was a member of the Hsp70 family and suggested that its origin was from duplication of a common ancestral gene. Transcript induction data, presence of several putative stress-responsive transcription factor-binding sites in the promoter region of PgHsc70 and the presence of a protective in vitro chaperone activity of this protein against damage caused by heat and salinity, when expressed in E. coli, suggest its probable role in conferring abiotic stress tolerance to this plant.
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Abbreviations
- ABA:
-
Abscisic acid
- ATP:
-
Adenosine triphosphate
- Hsc70:
-
Heat-shock cognate protein 70
- HSE:
-
Heat-shock element
- RE assay:
-
Restriction enzyme assay
- SA:
-
Salicylic acid
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This work was supported in part by the Department of Biotechnology (Ministry of Science and Technology, Government of India) in terms of a research grant and from internal grants of ICGEB.
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Communicated by C. Gebhardt.
PgHsc70 cDNA Acc# GQ254653; PgHsc70 Genomic sequence Acc# GQ979966; PgHsc70 Promoter Acc# EU620496.
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Reddy, P.S., Mallikarjuna, G., Kaul, T. et al. Molecular cloning and characterization of gene encoding for cytoplasmic Hsc70 from Pennisetum glaucum may play a protective role against abiotic stresses. Mol Genet Genomics 283, 243–254 (2010). https://doi.org/10.1007/s00438-010-0518-7
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DOI: https://doi.org/10.1007/s00438-010-0518-7