SCAN: The biosynthesis of di-myo-inositol-phosphate and related osmolytes involves genes and enzymes unique to hyperthermophiles

SCAN Seminar

Abstract:
Compatible solutes are low molecular mass compounds accumulating in many halophilic microorganisms to maintain an appropriate cell turgor and preserve the functionality of enzymes and other cell components. Many hyperthermophiles are isolated from shallow or abyssal marine geothermal areas, and like most marine organisms, they developed strategies of adaptation to the osmolarity conditions in the external medium. Di-myo-inositol-phosphate (DIP), glycerophosphoinositol (GPI), mannosyl-di-myo-inositol-phosphate (MDIP) and di-mannosyl-di-myo-inositol-phosphate (MMDIP) are compatible solutes found only in organisms with optimal growth temperature above 60 oC. To understand the role of these solutes in the mechanisms leading to osmo- and thermotolerance basic knowledge on their biosynthesis is mandatory. We focused on inositol-containing solutes, given the high correlation between the accumulation of this type of solutes and adaptation to hot environments. The biosynthesis of DIP and GPI was elucidated in the hyperthermophilic archaeon Archaeoglobus fulgidus, while the biosynthesis of MDIP and MMDIP was elucidated in the hyperthermophilic bacterium Thermotoga maritima. The relevant activities were sought in cell extracts using a variety of plausible substrates, and the products were characterized by NMR spectroscopy. The genes encoding the synthases were identified and the respective activities were confirmed by functional expression in E. coli. Furthermore, recombinant mannosyl-di-myo-inositol-phosphate synthase was produced, purified and biochemically characterized. This is a novel mannosyl transferase and the first enzyme ever reported to use DIP as a substrate.

Short CV:
1999-2004 - Degree in Biochemistry by Faculdade de Ciências da Universidade de Lisboa.
2004-2005. Research student in Cell Physiology and NMR group (ITQB) under the supervision of Prof. Helena Santos.Research area: New applications for compatible solutes from extremophiles.
2006-present. PhD student in Cell Physiology and NMR group (ITQB) under the supervision of Prof. Helena Santos. Research area: Role of phosphodiester osmolytes in thermoadaptation of hyperthermophiles: biosynthesis, regulation and applications.