Production of highly phosphorylated glycopolymers by expression of R1 in Escherichia coli.
The possible involvement of the starch bound R1 protein from potato (Solanum tuberosum L.) in the phosphorylation of starch was investigated by functional expression and characterisation of R1 in Escherichia coli. By expression of R1 in E. coli it is shown that it is possible to produce glycopolymers, e.g., glycogen, with an increased degree of phosphate substitution. The expression of R1 in E. coli resulted in a sixfold increase in glycogen bound phosphate and in an increased accumulation of glycogen leading to a glycogen excess (gex) phenotype. There was an overall shift in the unit-chain length of the isolated glycogen towards smaller degrees of polymerisation. The pleiotropic effects on the glycogen biosynthetic and amylolytic enzyme activities was investigated and showed an increase in ADPglucose pyrophosphorylase activity, as well as a decrease in exo-amylolytic activity. These results are discussed in relation to starch phosphorylation and a possible role of R1 in this respect.
Viksø-Nielsen
Anders
A
Plant Biochemistry Laboratory, Department of Plant Biology, Centre for Molecular Plant Physiology (PlaCe), Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 C, Frederiksberg, Denmark.
Hao-Jie Chen
Patrick
P
Larsson
Håkan
H
Blennow
Andreas
A
Møller
Birger Lindberg
BL
D015061:1,4-alpha-Glucan Branching Enzyme / Q000378:metabolism; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D051599:Glucose-1-Phosphate Adenylyltransferase; D006003:Glycogen / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000378:metabolism*; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011198:Solanum tuberosum; D013213:Starch / Q000378:metabolism*
D010940:Plant Proteins; D013213:Starch; D006003:Glycogen; D006006:Glycogen Synthase; D015061:1,4-alpha-Glucan Branching Enzyme; D009713:Nucleotidyltransferases; D051599:Glucose-1-Phosphate Adenylyltransferase