Lactobacillus reuteri 2′-Deoxyribosyltransferase, a Novel Biocatalyst for Tailoring of Nucleosides

Abstract

ABSTRACT A novel type II nucleoside 2′-deoxyribosyltransferase from Lactobacillus reuteri ( Lr NDT) has been cloned and overexpressed in Escherichia coli . The recombinant Lr NDT has been structural and functionally characterized. Sedimentation equilibrium analysis revealed a homohexameric molecule of 114 kDa. Circular dichroism studies have showed a secondary structure containing 55% α-helix, 10% β-strand, 16% β-sheet, and 19% random coil. Lr NDT was thermostable with a melting temperature ( T m ) of 64°C determined by fluorescence, circular dichroism, and differential scanning calorimetric studies. The enzyme showed high activity in a broad pH range (4.6 to 7.9) and was also very stable between pH 4 and 7.9. The optimal temperature for activity was 40°C. The recombinant Lr NDT was able to synthesize natural and nonnatural nucleoside analogues, improving activities described in the literature, and remarkably, exhibited unexpected new arabinosyltransferase activity, which had not been described so far in this kind of enzyme. Furthermore, synthesis of new arabinonucleosides and 2′-fluorodeoxyribonucleosides was carried out.