Glycogen phosphorylase, the product of the glgP Gene, catalyzes glycogen breakdown by removing glucose units from the nonreducing ends in Escherichia coli.
To understand the biological function of bacterial glycogen phosphorylase (GlgP), we have produced and characterized Escherichia coli cells with null or altered glgP expression. glgP deletion mutants (DeltaglgP) totally lacked glycogen phosphorylase activity, indicating that all the enzymatic activity is dependent upon the glgP product. Moderate increases of glycogen phosphorylase activity were accompanied by marked reductions of the intracellular glycogen levels in cells cultured in the presence of glucose. In turn, both glycogen content and rates of glycogen accumulation in DeltaglgP cells were severalfold higher than those of wild-type cells. These defects correlated with the presence of longer external chains in the polysaccharide accumulated by DeltaglgP cells. The overall results thus show that GlgP catalyzes glycogen breakdown and affects glycogen structure by removing glucose units from the polysaccharide outer chains in E. coli.
Alonso-Casajús
Nora
N
Agrobioteknologiako Instituta, Nafarroako Unibertsitate Publikoa and Consejo Superior de Investigaciones Científicas, Mutiloako etorbidea zenbaki gabe, 31192 Mutiloabeti, Nafarroa, Spain.
Dauvillée
David
D
Viale
Alejandro Miguel
AM
Muñoz
Francisco José
FJ
Baroja-Fernández
Edurne
E
Morán-Zorzano
María Teresa
MT
Eydallin
Gustavo
G
Ball
Steven
S
Pozueta-Romero
Javier
J
D001483:Base Sequence; D017931:DNA Primers; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005838:Genotype; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D024981:Glycogen Phosphorylase / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000378:metabolism
D017931:DNA Primers; D029968:Escherichia coli Proteins; D011135:Polysaccharides, Bacterial; D006003:Glycogen; D024981:Glycogen Phosphorylase; D005947:Glucose