%0 Journal Article %T Insights on the evolution of trehalose biosynthesis %A Nelson Avonce %A Alfredo Mendoza-Vargas %A Enrique Morett %A Gabriel Iturriaga %J BMC Evolutionary Biology %D 2006 %I BioMed Central %R 10.1186/1471-2148-6-109 %X In this study we show that trehalose biosynthesis ability is present in eubacteria, archaea, plants, fungi and animals. In bacteria there are five different biosynthetic routes, whereas in fungi, plants and animals there is only one. We present phylogenetic analyses of the trehalose-6-phosphate synthase (TPS) and trehalose-phosphatase (TPP) domains and show that there is a close evolutionary relationship between these domains in proteins from diverse organisms. In bacteria TPS and TPP genes are clustered, whereas in eukaryotes these domains are fused in a single protein.We have demonstrated that trehalose biosynthesis pathways are widely distributed in nature. Interestingly, several eubacterial species have multiple pathways, while eukaryotes have only the TPS/TPP pathway. Vertebrates lack trehalose biosynthetic capacity but can catabolise it. TPS and TPP domains have evolved mainly in parallel and it is likely that they have experienced several instances of gene duplication and lateral gene transfer.One of the fundamental challenges for an organism is to survive changes in the physical environment-mainly extreme temperatures, salinity, or dehydration. This problem was to be solved very early in evolution since the first cells inhabited the primitive seas [1,2]. Organisms evolved two different strategies to contend with abiotic stress. In certain species that live in extreme environments, for instance strict thermophiles and halophiles, the metabolic capabilities were modified, such that the optimal enzymatic activity or membrane stability are at high temperature or salinity, respectively [3]. Other organisms when exposed to extreme conditions have a drastically different adaptation to contend with stress. They evolved biosynthetic pathways for osmotically active compounds, cryoprotectants or thermoprotectants, thus enabling survival until conditions are favourable again. Among these compounds are polyols such as mannitol, sorbitol, some amino acids (proline and glu %U http://www.biomedcentral.com/1471-2148/6/109