Genetic engineering of plant secondary metabolism. Accumulation of 4-hydroxybenzoate glucosides as a result of the expression of the bacterial ubiC gene in tobacco.
The ubiC gene of Escherichia coli encodes chorismate pyruvatelyase, an enzyme that converts chorismate into 4-hydroxybenzoate (4HB) and is not normally present in plants. The ubiC gene was expressed in Nicotiana tabacum L. plants under control of a constitutive plant promoter. The gene product was targeted into the plastid by fusing it to the sequence for the chloroplast transit peptide of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. Transgenic plants showed high chorismate pyruvate-lyase activity and accumulated 4HB as beta-glucosides, with the glucose attached to either the hydroxy or the carboxyl function of 4HB. The total content of 4HB glucosides was approximately 0.52% of dry weight, which exceeded the content of untransformed plants by at least a factor of 1000. Feeding experiments with [1,7-13C2]shikimic acid unequivocally proved that the 4HB that was formed in the transgenic plants was not derived from the conventional phenylpropanoid pathway but from the newly introduced chorismate pyruvate-lyase reaction.
Siebert
M
M
Pharmazeutisches Institut, Universität Tübingen, Germany.
Sommer
S
S
Li
S M
SM
Wang
Z X
ZX
Severin
K
K
Heide
L
L
D000595:Amino Acid Sequence; D001483:Base Sequence; D002451:Cell Compartmentation; D002827:Chorismic Acid / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005818:Genetic Engineering / Q000379:methods*; D005822:Genetic Vectors; D005960:Glucosides / Q000096:biosynthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D007652:Oxo-Acid-Lyases / Q000235:genetics / Q000378:metabolism*; D010226:Parabens / Q000737:chemistry / Q000378:metabolism*; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D018087:Plastids / Q000378:metabolism; D021382:Protein Sorting Signals / Q000096:biosynthesis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis / Q000235:genetics; D012765:Shikimic Acid / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
D005960:Glucosides; D010226:Parabens; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D012765:Shikimic Acid; D012273:Ribulose-Bisphosphate Carboxylase; D007652:Oxo-Acid-Lyases; C075960:chorismate pyruvate lyase; D002827:Chorismic Acid; C038193:4-hydroxybenzoic acid