To be or not to be a compatible solute: Bioversatility of mannosylglycerate and glucosylglycerate

Abstract

To be or not to be a compatible solute: Bioversatility of mannosylglycerate and glucosylglycerate Nuno Empadinhas, Milton S. da Costa à Department of Biochemistry, Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal Received 30 April 2008Abstract Mannosylglycerate (MG) is an intracellular organic solute found in some red algae, and several thermophilic bacteria and hyperthermophilic archaea. Glucosylglycerate (GG) was identified at the reducing end of a polysaccharide from mycobacteria and in a free form in a very few mesophilic bacteria and halophilic archaea. MG has a genuine role in the osmoadaptation and possibly in thermal protection of many hyper/thermophilic bacteria and archaea, but its role in red algae, where it was identified long before hyperthermophiles were even known to exist, remains to be clarified. The GG-containing polysaccharide was initially detected in Mycobacterium phlei and found to regulate fatty acid synthesis. More recently, GG has been found to be a major compatible solute under salt stress and nitrogen starvation in a few microorganisms. This review summarizes the occurrence and physiology of MG accumulation, as well as the distribution of GG, as a free solute or associated with larger macromolecules. We also focus on the recently identified pathways for the synthesis of both molecules, which were elucidated by studying hyper/thermophilic MGaccumulating organisms. The blooming era of genomics has now allowed the detection of these genes in fungi and mosses, opening a research avenue that spans the three domains of life, into the role of these two sugar derivatives.

Ecological Genomics of Marine Picocyanobacteria

“…The occurrence of BetP, even in strains having no known capacity for synthesizing GB, indicates that this transporter could be used to take up GB released from other cells in the microbial community. Searches of marine Synechococcus genomes for genes involved in the biosynthesis of additional compatible solutes not previously found among cyanobacteria revealed two genes for the biosynthesis of GGA, a compatible solute known from a few bacteria to protect against salt stress, especially under nitrogen-limiting conditions (69). The structure of GGA is very similar to that of GG, but this compound is charged, which is unusual for classical compatible solutes.…”

Molecular biology of cyanobacterial salt acclimation

“…GGA resembles GG, but it is negatively charged (Fig. However, the role of GGA as a true compatible solute in heterotrophic bacteria is a matter of discussion (Empadinhas & da Costa, 2008b). As might be expected, given their structural similarities, GGA biosynthesis is similar to that of GG; it involves a glucosyltransferase, called glucosyl-phosphoglycerate synthase (GpgS), that uses ADP-as well as UDP-glucose and glycerate-3-phosphate, and the intermediate GGA-phosphate is hydrolyzed to GGA by the specific phosphatase glucosyl-phosphoglycerate phosphatase (GpgP).…”

Structural determination of the O-chain polysaccharide from the haloalkaliphilic Halomonas alkaliantarctica bacterium strain CRSS

“…32 The samples were analysed on an Agilent Technologies gas chromatograph 6850A equipped with a mass selective detector 5973 N and a Zebron ZB-5 capillary column (Phenomenex, 30 m  0.25 mm i.d., flow rate 1 mL/min, He as carrier gas). Acetylated methyl glycosides were analysed accordingly with the following temperature programme: 150°C for 3 Figure 3. Anomeric region of 1 H, 1 H NOESY spectrum of the O-chain polysaccharide from Halomonas alkaliantarctica performed at 315 K. The spectrum was recorded in D 2 O at 400 MHz.…”