Glass-forming property of hydroxyectoine is the cause of its superior function as a desiccation protectant

Abstract

We were able to demonstrate that hydroxyectoine, in contrast to ectoine, is a good glass-forming compound. Fourier transform infrared and spin label electron spin resonance studies of dry ectoine and hydroxyectoine have shown that the superior glass-forming properties of hydroxyectoine result from stronger intermolecular H-bonds with the OH group of hydroxyectoine. Spin probe experiments have also shown that better molecular immobilization in dry hydroxyectoine provides better redox stability of the molecules embedded in this dry matrix. With a glass transition temperature of 87°C (vs. 47°C for ectoine) hydroxyectoine displays remarkable desiccation protection properties, on a par with sucrose and trehalose. This explains its accumulation in response to increased salinity and elevated temperature by halophiles such as Halomonas elongata and its successful application in ``anhydrobiotic engineering'' of both enzymes and whole cells.

Crystal Structure of the Ectoine Hydroxylase, a Snapshot of the Active Site

“…7 and 8) is probably flexible enough to allow chemical modifications of these existing synthetic molecules. An EctD-mediated hydroxylation might endow them with novel stress-protective and structure-preserving functions in the same way that it allows 5-hydroxyectoine to function strikingly different from ectoine in alleviating desiccation stress (36).…”

A New Physiological Role for the DNA Molecule as a Protector against Drying Stress in Desiccation-Tolerant Microorganisms

“…One of these mechanisms includes the production and accumulation of biomolecules, termed xeroprotectants, which protect such essential biomolecules. In general, xeroprotectants are rich in hydroxyl groups that include trehalose and the pyrimidine derivatives ectoine and hydroxyectoine (also known as tetrahydropyrimidine-A and -B, respectively), which have been described as glass-forming molecules involved in tolerance to desiccation and osmosis in many organisms (Lippert and Galinski, 1992; Louis et al, 1994; Manzanera et al, 2002, 2004a,b; Tanne et al, 2014). Ectoine and hydroxyectoine show structural similarities to the pyrimidine bases (Kurz, 2008).…”

Different strategies of osmoadaptation in the closely related marine myxobacteria Enhygromyxa salina SWB007 and Plesiocystis pacifica SIR-1

“…Our results indicate that in addition to betaine the marine strain acquired, or retained, the ability to use hydroxyectoine as the main compatible solute. Hydroxyectoine, a derivative of ectoine, is widespread among halophilic bacteria, and compared with ectoine it provides better protection against various stress conditions, especially desiccation and heat (Lippert & Galinski, 1992;Louis et al, 1994;Tanne et al, 2014). In the intertidal zones of the littoral environment, desiccation is at least a temporary stress factor.…”