Molecular cloning and expression analysis of a cytosolic Hsp70 gene from Ulva pertusa (Ulvophyceae, Chlorophyta)

Abstract

In this study, homologous cloning coupled with the rapid amplification of cDNA ends was used to clone a full-length cytosolic heat shock protein 70 of Ulva pertusa (designated as UPHsp70). Bioinformatics was used to analyze structural features, homologous relationship, and phylogenetic position of UPHsp70. The full length of UPHsp70 cDNA was 2,283 bp, with a 5′ untranslated region of 65 bp, a 3′ untranslated region of 247 bp, and an open reading frame of 1,971 bp encoding a polypeptide of 656 amino acids with an estimated molecular weight of 71.13 kDa and an estimated isoelectric point of 5.04. The UPHsp70 had four degenerate repeats of tetrapeptide GGMP and three typical Hsp70 signature motifs. The specific C-terminus amino acid sequence of cytosolic UPHsp70 was EEVD, and the conservation of Hsp70s of N-terminus was higher than that of C-terminus. The homology between UPHsp70 and Hsp70s of other known algae and land plants was more than 70%. Under different stress conditions, mRNA expression levels of UPHsp70 were quantified by quantitative reverse transcriptasepolymerase chain reaction. When U. pertusa samples were kept in different temperatures (5-40°C) for 1 h, the expression level of UPHsp70 at 5°C, 35°C, or 40°C was over onefold higher than that at 25°C. When U. pertusa samples were kept at 30°C for different times (0-12 h), the mRNA expression level of UPHsp70 had a trend of rise first then fall. The expression level of UPHsp70 reached maximum level after 5 h. When U. pertusa samples were kept in different salt concentrations (0-45‰) for 2 h, the expression level of UPHsp70 at 0‰ or 5‰ salt concentration was twofold higher than that at 30‰ for 2 h. The expression levels of UPHsp70 at 30‰, 35‰, and 40‰ were low and had no difference (P<0.05). When U. pertusa samples were kept at ultraviolet irradiation or desiccated for different times (0-4 h), the mRNA expression level of UPHsp70 reached maximum level after 3.0 h; after that, it was maintained at high level.

Characterization and expression analysis of hsp70 gene from Ulva prolifera J. Agardh (Chlorophycophyta, Chlorophyceae)

“…Different from U. pertusa (Fu et al, 2011), the hsp70 transcription in U. prolifera was less affected by desiccation; it indirectly reflected that U. prolifera exhibited less adaption to desiccation. This was consistent with previous studies in which photosynthetic of U. pertusa showed little difference after the desiccation treatment (Zou and Gao, 2003;Guo and Dong, 2008).…”

“…Yokthongwattana et al (2001) studied hsp70 activities in the photosystem II damage and repairing in Dunaliella salina. In addition, Fu et al (2011) found that there was a correlation between transcriptions and stress induction in Ulva pertusa and held that hsp70 played an important role in the stresses.…”

Non-cryogenic preservation of thalli, germlings, and gametes of the green seaweed Ulva rigida

“…This may potentially be related to gene regulation induced by cold shock as it was found that overexpression of ERG10 enhanced survival and growth of yeast when frozen at -200 o C for five days (Rodriguez-Vargas et al, 2002). Whereas the expression of heat shock proteins (HSP) was not determined in the current study, HSP gene clones are available for U. pertusa (Tominaga et al, 2010) and U. prolifera (Fu et al, 2011). The subsequent decrease in regrowth rate with time may relate to bacterial activity and the subsequent mortality of the Ulva germlings.…”

Molecular cloning and functional analysis of small heat shock protein 19.1 gene from the Chinese oak silkworm, Antheraea pernyi

“…The expression level of Ap‐sHSP 19.1 gene was low in cold conditions and significantly elevated in response to temperature increase. However, Ap‐sHSP 19.1 expression was significantly decreased after exposure to high temperature stress (50°C; Figure ), this may be considered as the activity of enzymes related to the HSP mRNA synthesis was inhibited by high temperature (Fu et al, ; Wei et al, ). Our data suggest that the Ap‐sHSP19.1 gene plays a crucial role in thermal tolerance.…”