Heat Shock Protein Gene Family of the Porphyra seriata and Enhancement of Heat Stress Tolerance by PsHSP70 in Chlamydomonas

Abstract

Heat shock proteins and molecular chaperones are key components contributing to survival in the abiotic stress response. Porphyra seriata grows on intertidal rocks exposed to dynamic environmental changes associated with the turning tides, including desiccation and heat stress. Analysis of the ESTs of P. seriata allows us to identify the nine HSP cDNAs, which are predicted to be PsHSP90, three PsHSP70, PsHSP40 and PsHSP20, and three 5'-truncated HSP cDNAs. RT-PCR results show that most of the PsHSP transcripts were detected under normal cell growth conditions as well as heat stress, with the exception of two cDNAs. In particular, PsHSP70b and PsHSP20 transcripts were upregulated by heat stress. When the putative mitochondrial PsHSP70b was introduced and overexpressed in Chlamydomonas, transformed Chlamydomonas evidenced higher rates of survival and growth than those of the wild type under heat stress conditions. Constitutive overexpression of the PsHSP70b gene increases the transcription of the HSF1 as well as the CrHSP20 and CrHSP70 gene. These results indicate that PsHSP70b is involved in tolerance to heat stress and the effects on transcription of the CrHSP20 and CrHSP70 genes.

Overexpression of a Brassica campestris HSP70 in tobacco confers enhanced tolerance to heat stress

“…Multiple alignments and bioinformatics analysis results showed that the deduced BcHSP70 had high similarity to other plant HSP70s and had the clearest relationship to AtHSP70-4. Deduced BcHSP70 protein of the isolated BcHSP70 cDNA exhibited conserved motif and domains with reported HSP70s from other reported plant such as A. thaliana and N. tabacum (Lin et al 2001;Cho and Hong 2004), which indicated that those domains are very important for maintaining the function of HSP (Guy and Li 1998;Montero-Barrientos et al 2010;Park et al 2012). In addition, BcHSP70 possessed a cytosolic compartment sequence, GPKIEEVD, at the C-terminal (Boorstein et al 1994;Guy and Li 1998;Tom et al 1999), suggesting that BcHSP70 may be located in the cytosolic region.…”

“…For example, HSP70 was found necessary for heat stress tolerance in Arabidopsis thaliana (Su and Li 2008). Introduction of HSP70 from Porphyra seriata into Chlamydomonas can effectively enhance the latter's tolerance to heat stress (Park et al 2012).…”

A Chrysanthemum Heat Shock Protein Confers Tolerance to Abiotic Stress

“…When the rice mitochondrial HSP70 gene ( mtHsp70 ) was constitutively expressed in rice suspension culture cells, heat stress proved less potent in inducing apoptosis [22]. The heterologous expression of the Porphyra seriata mitochondrial gene PsHSP70b in Chlamydomonas improved survival and cell growth under heat stress conditions [23]. Drought stress tolerance proved also to be enhanced when NtHSP70-1 was over-expressed [24].…”

De novo assembly of transcriptome from the gametophyte of the marine red algae Pyropia seriata and identification of abiotic stress response genes

“…HSPs play an essential role in protecting cells, regulating nascent protein folding and translocation, refolding of denatured proteins, and the disassembly of protein aggregates under both stressed and non-stressed conditions (Bray et al 2000;Feder and Hofmann 1999;Schroda and Vallon 2009). Under stress conditions, HSP70s are upregulated, participate in the refolding of denatured proteins, maintain cell homeostasis, and protect organisms against damage (Mayer and Bukau 2005;Park et al 2011). A previous report shows that an HSP70 from P. seriata responds to high temperature and is involved in thermotolerance .…”