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The compatible solute ectoine: protection mechanisms, strain development, and industrial production
(2020)
Bacteria, Archaea, and Eukarya can adapt to saline environments by accumulating compatible solutes in order to maintain an osmotic equilibrium. Compatible solutes are of diverse chemical structure (sugars, polyols, amino acid derivatives) and are beneficial for bacterial cells not only as osmoregulatory solutes but also as
protectants of proteins by mitigating detrimental effects of freezing, drying, and high temperatures. The aspartate derivative ectoine is a widespread compatible solute in Bacteria and possesses additional protective properties compared with other compatible solutes and stabilizes even whole cells against stresses such as ultraviolet radiation or cytotoxins. Here, it is our intention to go beyond a simple description of effects, but to depict the molecular interaction of ectoine with biomolecules, such as proteins, membranes, and DNA and explain the underlying principles. The stabilizing properties of ectoine attracted industry, which saw the potential to market ectoine
as a novel active component in health care products and cosmetics. In joint efforts of industry and research, a large-scale fermentation procedure has been developed with the halophilic bacterium Halomonas elongata used as a producer strain. The development and application of ectoine-excreting mutants from H. elongata (“leaky” mutants) allow for the annual production of ectoine on a scale of tons. The details of
the strain development and fermentation processes will be introduced.
What Does Ectoine Do to DNA? A Molecular-Scale Picture of Compatible Solute−Biopolymer Interactions
(2020)
Compatible solutes are accumulated in the cytoplasm of halophilic microorganisms. These molecules enable their survival in a high salinity environment. Ectoine is such a compatible solute. It is a zwitterionic molecule which strongly interacts with surrounding water molecules and changes the dynamics of the local hydration shell. Ectoine interacts with biomolecules such as lipids, proteins and DNA. The molecular interaction between ectoine and biomolecules in particular the interaction between ectoine and DNA is far from being understood.
In this paper we describe molecular aspects of the interaction between ectoine and double stranded DNA(dsDNA). Two 20 base pairs long dsDNA fragments were immobilized on a Gold surface via a thiol-tether. The interaction between the dsDNA monolayers with diluted and concentrated ectoine solutions was examined by means of X-ray photoelectron and polarization modulation infrared reflection absorption spectroscopies (PM IRRAS). Experimental results indicate that the ability of ectoine to bind water reduces the strength of hydrogen bonds formed to the ribose-phosphate backbone in the dsDNA. In diluted (0.1 M) ectoine solution, DNA interacts predominantly with water molecules. The sugar-phosphate backbone is involved in the formation of strong hydrogen bonds to water, which with elapsing time leads to a reorientation of the planes of nucleic acid bases. This reorientation destabilizes the hydrogen bonds strength between the bases and leads to a partial dehybridizaiton of the dsDNA. In concentrated ectoine solution (2.5 M), almost all water molecules interact with ectoine. Under this condition ectoine is able to interact directly with DNA. Density functional theory (DFT) calculations demonstrate that the direct interaction involves the nitrogen atoms in ectoine and phosphate groups in the DNA molecule. The results of the quantum chemical calculations Show that rearrangements in the ribose-phosphate backbone, caused by a direct interaction with ectoine, facilitates contacts between O atom in the phosphate group and H atoms in a nucleic acid base. In the PM IRRA spectra, an increase in the number of the IR absorption modes in the base pair frequency region proves that the hydrogen bonds between bases become weaker.
Thus, a sequence of reorientations caused by interaction with ectoine leads to a breakdown of hydrogen bonds between bases in the double helix.