Alcaide, M., Stogios, P.J., Lafraya, A., Tchigvintsev, A., Flick, R., Bargiela, R., Chernikova, T.N., Reva, O.N., Hai, T., Leggewie, C.C., Katzke, N., La Cono, V., Matesanz, R., Jebbar, M., Jaeger, K.E., Yakimov, M.M., Yakunin, A.F., Golyshin, P.N., Golyshina, O.V., Savchenko, A., Ferrer, M.
The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5 degrees C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65 degrees C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16 degrees C, was shown to contain halopiezophilic-like enzymes that are most active at 70 degrees C and with denaturing temperatures of 71.4 degrees C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes.
        
Representative scheme of GTSAGmotif structure and an image from PDBsum server
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4Q3O Previously Class, Architecture, Topology and Homologous superfamily - PDB-Sum server
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4Q3OFold classification based on Structure-Structure alignment of Proteins - FSSP server