engleski

Natively unfolded regions lower the solvation free energy in proteins: a putative role in the desiccation-resistant bacterium Deinococcus radiodurans

A protein belonging to the Nudix hydrolase family found in the radio-resistant and desiccation-tolerant bacterium Deinococcus radiodurans possesses an 82-residue low-complexity N-terminal tail, which is likely to be natively unfolded and has unknown function. Most importantly, the tail is not present in other non-extremophile homologs. The enzyme catalyzes the hydrolysis of oxidatively damaged and mutagenic nucleotides and it is thought to play an important role during the recovery phase of D. radiodurans after being exposed to ionizing radiation or desiccation. By using atomistic simulations and computational methods to: 1) study the dynamics of the protein and 2) calculate its solvation free energy with and without the N-terminal tail using the generalized Born formalism, we show that the presence of the tail significantly decreases the solvation free energy of the whole protein. We hypothesize that this precisely is the function of the tail: it increases the chances of the protein to be located in the remaining water patches in the desiccated cell, where it is protected from the desiccation effects and can function normally. We extrapolate this to other natively unfolded regions in proteins, and propose a novel function for them: natively unfolded regions increase the <<surface-properties>> of folded domains they are attached to, making a given protein on the whole more hydrophilic and influencing in this way its localization and cellular activity.

natively unfolded proteins; Deinococcus radiodurans; desiccation; solvation free energy

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