T. Tobimatsu et al., Specificities of reactivating factors for adenosylcobalamin-dependent dioldehydratase and glycerol dehydratase, ARCH MICROB, 174(1-2), 2000, pp. 81-88
Adenosylcobalamin-dependent glycerol and diol dehydratases undergo inactiva
tion by the physiological substrate glycerol during catalysis. In the perme
abilized cells of Klebsiella pneumoniae, Klebsiella oxytoca, and recombinan
t Escherichia coli, glycerol-inactivated glycerol dehydratase and diol dehy
dratase are reactivated by their respective reactivating factors in the pre
sence of ATP, Mg2+, and adenosylcobalamin. Both of the reactivating factors
consist of two subunits. To examine the specificities of the reactivating
factors, their genes or their hybrid genes were co-expressed with dehydrata
se genes in E. coli cells in various combinations. The reactivating factor
of K. oxytoca for diol dehydratase efficiently cross-reactivated the inacti
vated glycerol dehydratase, whereas the reactivating factor of K. pneumonia
e for glycerol dehydratase hardly cross-reactivated the inactivated diol de
hydratase. Both of the two hybrid reactivating factors rapidly reactivated
the inactivated glycerol dehydratase. In contrast, the hybrid reactivating
factor containing the large subunit of the glycerol dehydratase reactivatin
g factor hardly reactivated the inactivated diol dehydratase. These results
indicate that the glycerol dehydratase reactivating factor is much more sp
ecific for the dehydratase partner than the diol dehydratase reactivating f
actor and that a large subunit of the reactivating factors principally dete
rmines the specificity for a dehydratase.