Marie Curie Conference location:Barcelona, Spain date:17-18 July 2008
It is very difficult to imagine the live without water as actually it seems that loss of water unquestionably leads to death. However, some organisms evolved mechanisms to survive extreme drought as the loss of 99% of their water content does not prevent them from resuming their life after water addition. This kind of phenomena is known as “cryptobiosis”, it has been found in some fungi, nematodes, crustacean, tardigrades, and a few plants. One of the most useful strategies to survive long dry periods is the synthesis and high accumulation of trehalose, a sugar containing two glucose moieties. So far there are described five trehalose biosynthetic pathways, but the most widely distributed involves the action of two enzymes called trehalose 6-phosphate synthase (TPS) and trehalose 6-phosphate phosphatase (TPP). Apart from its presence in cryptobiotic organisms, trehalose is also produced by many other organisms where it functions as energy and carbon reserve, to protect against oxygen radicals, as a structural compound of bacterial cell walls, or as a sensing molecule. For many years our laboratory has been a leader in the characterization of yeast and plant trehalose biosynthetic genes, with a view on industrial applications as our main focus. Some examples are the cloning and characterization of several plant trehalose biosynthesis genes and their use to improve drought tolerance in transgenic plants and also the use of those genes as selection marker for plant transformation, avoiding the use of antibiotic resistance markers. Recently, we have cloned and characterized the first bifunctional TPS-TPP protein, a novel bacterial gene able to synthesize trehalose by itself. In this presentation we will show the results concerning the functional and phylogenetic characterization of the Cytophaga hutchinsonii TPSP gene and the whole TPS and TPP gene family of the smallest eukaryan organism Ostreococcus tauri, one of its closest relatives in the plant group. On one hand, our results clarify the evolutionary history of the complex plant TPS and TPP multigene families by adding insights to the role of these genes. On the other hand, our identification of the bifunctional ChTPSP protein opens new biotechnological opportunities to produce trehalose with a single gene and without the modification of trehalose 6-phosphate content, the intermediate metabolite that has been assigned as a new plant growth regulator.