A Selaginella lepidophyllaTrehalose-6-Phosphate Synthase Complements Growth and Stress-Tolerance Defects in a Yeasttps1Mutant1

Abstract

The accumulation of the disaccharide trehalose in anhydrobiotic organisms allows them to survive severe environmental stress. A plant cDNA, SlTPS1, encoding a 109-kD protein, was isolated from the resurrection plant Selaginella lepidophylla, which accumulates high levels of trehalose. Protein-sequence comparison showed that SlTPS1 shares high similarity to trehalose-6-phosphate synthase genes from prokaryotes and eukaryotes. SlTPS1 mRNA was constitutively expressed in S. lepidophylla. DNA gel-blot analysis indicated that SlTPS1 is present as a single-copy gene. Transformation of a Saccharomyces cerevisiae tps1⌬ mutant disrupted in the ScTPS1 gene with S. lepidophylla SlTPS1 restored growth on fermentable sugars and the synthesis of trehalose at high levels. Moreover, the SlTPS1 gene introduced into the tps1⌬ mutant was able to complement both deficiencies: sensitivity to sublethal heat treatment at 39°C and induced thermotolerance at 50°C. The osmosensitive phenotype of the yeast tps1⌬ mutant grown in NaCl and sorbitol was also restored by the SlTPS1 gene. Thus, SlTPS1 protein is a functional plant homolog capable of sustaining trehalose biosynthesis and could play a major role in stress tolerance in S. lepidophylla.

A bifunctional TPS–TPP enzyme from yeast confers tolerance to multiple and extreme abiotic-stress conditions in transgenic Arabidopsis

“…In yeast it is well known that trehalose is involved in heat tolerance (De Virgilio et al 1994;Zentella et al 1999). Here we found that transgenic lines expressing the TPS1-TPS2 gene fusion had a better capacity to tolerate heat stress.…”

“…The subcloning of TPS1 or TPS2 yeast genes in pSal4 has already been described (Zentella et al 1999). Yeast growth was at 30°C and the culture media and yeast strains (W303-1A wild type, tps1 , tps2 and tps1tps2 ) were described before (Zentella et al 1999). Transformation was performed as described previously (Elble 1992), and transformants were selected in minimal media without uracil.…”

“…There are at least Wve routes for trehalose biosynthesis (Avonce et al 2006) and the most widely distributed has been reported in several species of bacteria including E. coli, yeast, insects, and plants such as Arabidopsis thaliana and the so-called "resurrection plant" Selaginella lepidophylla (Zentella et al 1999). Trehalose metabolism has been studied in most detail in Saccharomyces cerevisiae.…”

Dehydration-induced tps gene transcripts from an anhydrobiotic nematode contain novel spliced leaders and encode atypical GT-20 family proteins

“…In plants, the C-terminal domain has been reported to show similarity to bacterial trehalose-6-phosphate phosphatase (TPP; exemplified by OtsB from E. coli) suggesting that both activities required for trehalose synthesis are contained within the same protein. Zentella et al [8] and Vogel et al [31] were unable to confirm TPP activity encoded by tps genes from S. lepidophylla and A. thaliana, respectively, however. This is perhaps not surprising, since the similarity between the plant C-terminal TPS and OtsB sequences is slight; more extensive is the relatedness between insect C-terminal TPS sequences and OtsB (data not shown), and it is likely that these TPP-related sequences are functional since the Drosophila TPS1 protein alone is able to direct trehalose synthesis in human cells [32].…”

“…Genes encoding the first of these enzymes (tps) have been identified in a wide range of organisms, including plants (e.g., Selaginella lepidophylla [8]), invertebrates (e.g., Caenorhabditis elegans [9]), yeast (e.g., Saccharomyces cerevisiae [10,11]) and bacteria (e.g., Escherichia coli [12]); trehalose-6-phosphate phosphatase genes have also been characterised for many micro-organisms. Although some of these organisms are anhydrobiotic (e.g., Se.…”