(National Academy of Sciences, 2001) Moreno Bruna, Beatriz; Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Bastarrica Berasategui, Ainara; Zandueta Criado, Aitor; Rodríguez López, Milagros; Lasa Uzcudun, Íñigo; Akazawa, Takashi; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
An adenosine diphosphate sugar pyrophosphatase (ASPPase, EC
3.6.1.21) has been characterized by using Escherichia coli. This
enzyme, whose activities in the cell are inversely correlated with
the intracellular glycogen content and the glucose concentration in
the culture medium, hydrolyzes ADP-glucose, the precursor molecule
of glycogen biosynthesis. ASPPase was purified to apparent
homogeneity (over 3,000-fold), and sequence analyses revealed
that it is a member of the ubiquitously distributed group of
nucleotide pyrophosphatases designated as ‘‘nudix’’ hydrolases.
Insertional mutagenesis experiments leading to the inactivation of
the ASPPase encoding gene, aspP, produced cells with marginally
low enzymatic activities and higher glycogen content than wildtype
bacteria. aspP was cloned into an expression vector and
introduced into E. coli. Transformed cells were shown to contain a
dramatically reduced amount of glycogen, as compared with the
untransformed bacteria. No pleiotropic changes in the bacterial
growth occurred in both the aspP-overexpressing and aspP-deficient
strains. The overall results pinpoint the reaction catalyzed by
ASPPase as a potential step of regulating glycogen biosynthesis in
E. coli.
