Abstract
BackgroundSacPox, an enzyme from the extremophilic crenarchaeal Sulfolobus acidocaldarius (Sac), was isolated by virtue of its phosphotriesterase (or paraoxonase; Pox) activity, i.e. its ability to hydrolyze the neurotoxic organophosphorus insecticides. Later on, SacPox was shown to belong to the Phosphotriesterase-Like Lactonase family that comprises natural lactonases, possibly involved in quorum sensing, and endowed with promiscuous, phosphotriesterase activity.ResultsHere, we present a comprehensive and broad enzymatic characterization of the natural lactonase and promiscuous organophosphorus hydrolase activities of SacPox, as well as a structural analysis using a model.ConclusionKinetic experiments show that SacPox is a proficient lactonase, including at room temperature. Moreover, we discuss the observed differences in substrate specificity between SacPox and its closest homologues SsoPox and SisLac together with the possible structural causes for these observations.
Highlights
SacPox, an enzyme from the extremophilic crenarchaeal Sulfolobus acidocaldarius (Sac), was isolated by virtue of its phosphotriesterase activity, i.e. its ability to hydrolyze the neurotoxic organophosphorus insecticides
Because OPs have been massively used as pesticides since the 50′s [8], PTEs are believed to have emerged in few decades from a Phosphotriesterase-Like Lactonases (PLLs) progenitor [2], providing a new source of phosphorus to bacteria, and a selective advantage [8]
SacPox belongs to the PLLs-A (Figure 2A) [2]: it shares 76.1% of sequence identity with its closest homologues SsoPox and SisLac, and only 30.6% identity with the PLL-B DrOPH
Summary
SacPox, an enzyme from the extremophilic crenarchaeal Sulfolobus acidocaldarius (Sac), was isolated by virtue of its phosphotriesterase (or paraoxonase; Pox) activity, i.e. its ability to hydrolyze the neurotoxic organophosphorus insecticides. Because OPs have been massively used as pesticides since the 50′s [8], PTEs are believed to have emerged in few decades from a PLL progenitor [2], providing a new source of phosphorus to bacteria, and a selective advantage [8]. Both enzyme families exhibit the same (β/α)8-barrel topology [9,10] and belong to the amidohydrolase superfamily [11,12].
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