J. Rebelo et al., Gene sequence and crystal structure of the aldehyde oxidoreductase from Desulfovibrio desulfuricans ATCC 27774, J MOL BIOL, 297(1), 2000, pp. 135-146
The aldehyde oxidoreductase (MOD) isolated from the sulfate reducer Desulfo
vibrio desulfuricans (ATCC 27774) is a member of the xanthine oxidase famil
y of molybdenum-containing enzymes. It has substrate specificity similar to
that of the homologous enzyme from Desulfovibrio gigas (MOP) and the prima
ry sequences from both enzymes show 68 % identity. The enzyme was crystalli
zed in space group P6(1)22, with unit cell dimensions of of a = b = 156.4 A
ngstrom and c = 177.1 Angstrom, and diffraction data were obtained to beyon
d 2.8 Angstrom. The crystal structure was solved by Patterson search techni
ques using the coordinates of the D. gigas enzyme. The overall fold of the
D. desulfuricans enzyme is very similar to MOP and the few differences are
mapped to exposed regions of the molecule. This is reflected in the electro
static potential surfaces of both homologous enzymes, one exception being t
he surface potential in a region identifiable as the putative docking site
of the physiological electron acceptor. Other essential features of the MOP
structure, such as residues of the active-site cavity, are basically conse
rved in MOD. Two mutations are located in the pocket bearing a chain of cat
alytically relevant water molecules.
As deduced from this work, both these enzymes are very closely related in t
erms of their sequences as well as 3D structures. The comparison allowed co
nfirmation and establishment of features that are essential for their funct
ion; namely, conserved residues in the active-site, catalytically relevant
water molecules and recognition of the physiological electron acceptor dock
ing site. (C) 2000 Academic Press.