Resumen:
Structure-function relationships of a novel 20
-deoxyribosyltransferase from the
psychrotolerant bacterium Bacillus psychrosaccharolyticus (BpNDT) have been exhaustively studied
by biochemical and high resolution crystallographic analyses. Despite BpNDT exhibiting some
structural features characteristic of cold-adapted enzymes such as localized flexibility in critical
loops, its biochemical properties are typical of mesophilic enzymes. BpNDT is a highly symmetrical
homohexamer with tightly associated subunits that possesses flexible and short loops bordering
the active sites. The catalytic center is essentially identical to that of other mesophilic homologues.
Moreover, BpNDT shows that it is a mesophilic-like enzyme since it is not heat-labile and exhibits
an apparent unfolding temperature (Tm) of 49 ◦C, being active during 96 h at 40 and 50 ◦C. Finally,
BpNDT synthesizes natural and modified nucleosides, with preference for purines as acceptors and
pyrimidine nucleosides as donors. Remarkably, the synthesis of several therapeutic nucleosides
has been efficiently carried out. In this sense, 5-hydroxymethyl-20
-deoxyuridine (5-HMdUrd),
7-deaza-6-hydroxypurine-20
-deoxyriboside (7-D...