Novel arrangement and comparative analysis of hsp90 family genes in three thermotolerant species of Stratiomyidae (Diptera)

Abstract

The heat shock proteins belonging to the Hsp90 family (Hsp83 in Diptera) play a crucial role in the protection of cells due to their chaperoning functions. We sequenced hsp90 genes from three species of the family Stratiomyidae (Diptera) living in thermally different habitats and characterized by extraordinarily high thermotolerance. The sequence variation and structure of the hsp90 family genes were compared with previously described features of hsp70 copies isolated from the same species. Two functional hsp83 genes were found in the species studied, that are arranged in tandem orientation at least in one of them. This organization was not previously described. Stratiomyidae hsp83 genes share a high level of identity with hsp83 of Drosophila, and the deduced protein possesses five conserved amino acid sequence motifs characteristic of the Hsp90 family as well as the C-terminus MEEVD sequence characteristic of the cytosolic isoform. A comparison of the hsp83 promoters of two Stratiomyidae species from thermally contrasting habitats demonstrated that while both species contain canonical heat shock elements in the same position, only one of the species contains functional GAF-binding elements. Our data indicate that in the same species, hsp83 family genes show a higher evolution rate than the hsp70 family.

The polymorphisms in the promoter of HSP90 gene and their association with heat tolerance of bay scallop

“…Moreover, it is of note that there was one intron before the initiation codon and several promoter elements, including two transcription start sites, two TATA boxes, one CAAT box, and one HSE, were located in this region. Similar results have been described in the HSP90s of human (Shen et al 1997), Australian sheep blowfly (Concha et al 2012), and Stratiomyidae (Astakhova et al 2013), in which HSEs were detected in the intron of the HSP90 genes. Therefore, it is suspected that the intron found in the present study may be involved in the transcriptional regulation of AiHSP90 gene.…”

“…Though the fluctuation of HSP levels is not "a silver bullet" and organisms may exhibit different strategies for adaptation to adverse environmental conditions (Bedulina et al 2013;Mizrahi et al 2012), stress-induced synthesis of HSPs represents a generalized molecular mechanism for almost all cells (Basiricò et al 2011), and moreover, the expression timing and/or intensity of HSP90 were found to be different in various thermally adapted species in response to acute heat stress (Arad et al 2010;Astakhova et al 2013;Boher et al 2012;Sgrò et al 2008). By far, the induction of HSP90 synthesis by heat stress has previously been reported in various aquatic species (Manchado et al 2008;Pan et al 2000;Wu et al 2012;Zhang et al 2009); however, there were no comparative studies on the expression of HSP90 in different thermally adapted species of aquatic animals.…”

“…However, there were also some reports with inconsistent results. For example, in two Stratiomyidae species, though polymorphisms in the promoter region of HSP90 results in different binding activities for transcription factor GAF, which plays a crucial role in chromatin modification and provides fast switching on of HSPs genes in Drosophila (Omelina et al 2011), there was no drastic differences in HSP83 mRNA accumulation in the compared species under both normal physiological and heat stress conditions (Astakhova et al 2013).…”

“…Compared to the most studies performed under laboratory conditions, it is necessary to investigate related species or geographical populations of the same species inhabiting thermally contrasting habitats to elucidate the ecological role of HSP90 in nature (Feder and Hofmann 1999;Nollen and Morimoto 2002). By far, genetic variations in HSP90 genes of several organisms have been reported to be associated with heat tolerance traits, such as cattle (Charoensook et al 2012;Shergojry et al 2012), Drosophila (Blackman and Meselson 1986;Boher et al 2012;Hasson and Eanes 1996;Sgrò et al 2008), snail (Arad et al 2010), Stratiomyidae (Astakhova et al 2013), and yeast (Jarosz and Lindquist 2010). Especially, the studies focused on the association between genetic variations in HSP90 genes of Drosophila species and their ecological roles are arising.…”

Diversity and Adaptations of Immature Diptera in Semiaquatic Habitats at Shorelines of Hypersaline Lakes in the Crimea, with a Brief Review of Diptera in Mineralized Bodies of Water

“…In halophilous species, larvae display the higher thermotolerance and maintain higher concentrations of heat shock proteins (HSP70) both before and after heat shock (Garbuz et al, 2008(Garbuz et al, , 2010. In Stratiomyidae, halophilous species differ from those living in cold freshwaters in the organization of HSP70 and HSP83 genes and in the regulatory mechanisms of expression of these genes (Garbuz et al, 2008(Garbuz et al, , 2011Astakhova et al, 2013). …”