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

• Published in: Systematic and applied microbiology Vol. 31; no. 3; pp. 159 - 168
• Main Authors: Empadinhas, Nuno, da Costa, Milton S.
• Format: Journal Article
• Language: English
• Published: München Elsevier GmbH 01-08-2008; Elsevier
• Subjects: Adaptation, Physiological; algae and seaweeds; Archaea; Archaea - classification; Archaea - physiology; Bacteria - classification; Bacteria - metabolism; Bacterial Physiological Phenomena; biochemical pathways; Biological and medical sciences; Biosynthesis; Compatible solutes; Fundamental and applied biological sciences. Psychology; Fungi - metabolism; Glucosides - biosynthesis; Glucosides - chemistry; Glucosylglycerate; Glyceric Acids - chemistry; glycolipids; Hot Temperature; literature reviews; Mannose - analogs & derivatives; Mannose - biosynthesis; Mannose - chemistry; Mannosylglycerate; microbial genetics; Microbiology; Mycobacterium phlei; Nocardia; Osmolar Concentration; Persephonella marina; Rhodophyta - metabolism; Rubrobacter xylanophilus; solutes; sugar acids; thermophilic bacteria; Compatible solutes; Biosynthesis; Mannosylglycerate; Glucosylglycerate; Solutes; Metabolic pathway; Review; Biological accumulation
• ISSN: 0723-2020; 1618-0984
• DOI: 10.1016/j.syapm.2008.05.002

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 MG-accumulating 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.