title: Extremolyte-like applicability of an archaeal exopolymer, poly-gamma-L-glutamate.
abstract: An extremely halophilic archaeon Natrialba aegyptiaca produces extracellular poly-gamma-glutamate (PGA), in which only L-glutamate is polymerized via gamma-amide linkages. We examined the extremolyte-like applicability of archaeal PGA and found the ameliorating effects of L-PGA on the resistibility to freeze-thawing and proteolysis, thermostability, and alkalotolerance of a model enzyme, labile DNA ligase. For example, the coexistence of low (e.g. 0.01 mg mL(-1)) and high (e.g. 0.1 mg mL(-1)) concentrations of L-PGA with an average molecular mass of 1000 kDa increased the midpoint of thermal inactivation of DNA ligase by about 15 degrees C and 18 degrees C, respectively, and the model enzyme further remained active even under extremely alkaline conditions of pH 11.4 in the presence of the high concentration of L-PGA. This is the first characterization of the stereo-regular PGA molecules as atypical extremolytes. L-PGA from extremophiles has great potential as a bio-based protectant (or stabilizer) with industrial versatility.
authors: Graduate School of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors: Daisuke
authors: D
authors: Yamasaki
authors: Yutaka
authors: Y
authors: Minouchi
authors: Makoto
authors: M
authors: Ashiuchi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011088:DNA Ligases / Q000187:drug effects / Q000378:metabolism; D005110:Extracellular Space / Q000737:chemistry; D006216:Halobacteriaceae / Q000737:chemistry*; D009994:Osmolar Concentration; D011099:Polyglutamic Acid / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D020011:Protective Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D055550:Protein Stability
chemical_list: D001426:Bacterial Proteins; D020011:Protective Agents; D011099:Polyglutamic Acid; D011088:DNA Ligases