Metabolite phosphatase from anhydrobiotic tardigrades

Area of Science:

• Biochemistry
• Molecular Biology
• Extremophile Research

Background:

• Tardigrades exhibit remarkable anhydrobiosis (survival of severe dehydration).
• The molecular mechanisms underlying tardigrade desiccation tolerance are not fully understood.
• Ferritin-like proteins are upregulated in tardigrades during desiccation.

Purpose of the Study:

• To elucidate the molecular mechanisms of anhydrobiosis in the tardigrade Ramazzottius varieornatus.
• To investigate the function of a desiccation-upregulated Ferritin-like protein.
• To explore the role of this protein family in stress tolerance across different organisms.

Main Methods:

• Determined the atomic resolution crystal structure (1.05 Å) of the tardigrade Ferritin-like protein.
• Assayed the phosphatase activity of the protein against various metabolite compounds.
• Investigated a homologous protein from the extremophile bacterium Deinococcus radiodurans.

Main Results:

• The tardigrade Ferritin-like protein possesses a dinuclear metal binding site.
• This protein exhibits phosphatase activity, particularly on nucleotide phosphates damaged by oxidative or radiation stress.
• A homologous protein from Deinococcus radiodurans also functions as a metabolite phosphatase.

Conclusions:

• The Ferritin-like protein family, acting as metabolite phosphatases, likely contributes to desiccation and radiation stress tolerance.
• These enzymes may function by clearing damaged metabolites or regulating metabolite levels.
• This finding offers insight into a universal molecular basis for stress tolerance in terrestrial organisms.