Screening of microbial genomes towards new enzymes for the synthesis of compatible solutes

点击翻译按钮获取中文摘要

Acclimation of organisms to high salt concentrations usually includes the accumulation of compatible solutes. Compatible solutes are a functional group of small organic molecules, which can be accumulated in high cellular amounts without disturbing metabolism. Beside carbohydrates, polyols, amino acids and their derivates the group of heterosides (combination of sugar and polyol) is often found in cells of salt-loaded archaea, bacteria, algae and plants. Compared to other compatible solutes, heterosides are not well studied in general. But due to the chimeric chemical nature they cause interesting physiological effects. Like carbohydrates such as trehalose they mediate membrane and protein stabilization but seem to have higher osmoprotective efficiency such as true polyols. By a homology search for proteins with similarities to heteroside-synthesizing enzymes a high number of putative new enzymes was discovered in recently sequenced prokaryotic genomes. The phylogenetic analyses revealed an unexpected pattern, which may indicate that lateral gene transfer was involved in the distribution of this class of salt resistance genes . Within the scope of our research project we will functionally analyze those genes. Such results will improve our knowledge on mechanisms of basic salt acclimation strategies and may be useful to improve salt and desiccation tolerance of crop plants.