An Escherichia coli K-12 tktA tktB mutant deficient in transketolase activity requires pyridoxine (vitamin B6) as well as the aromatic amino acids and vitamins for growth.
We show that a tktA tktB double mutant, which is devoid of the two known transketolase isoenzymes of Escherichia coli K-12, requires pyridoxine (vitamin B6) as well as the aromatic amino acids and vitamins for growth. This pyridoxine requirement can also be satisfied by 4-hydroxy-L-threonine or glycolaldehyde. These results provide direct evidence that D-erythrose-4-phosphate is a precursor of the pyridine ring of pyridoxine. In addition, they show that the two major E. coli transketolase isoenzymes are not required for the biosynthesis of D-1-deoxyxylulose, which is thought to be another precursor of pyridoxine.
Zhao
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Department of Microbiology and Molecular Genetics, University of Texas Houston Medical School, Houston 77030-1501.
Winkler
M E
ME
D000596:Amino Acids / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D005798:Genes, Bacterial / Q000235:genetics; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011736:Pyridoxine / Q000378:metabolism*; D014174:Transketolase / Q000235:genetics / Q000378:metabolism*; D014815:Vitamins / Q000378:metabolism
D000596:Amino Acids; D007527:Isoenzymes; D014815:Vitamins; D014174:Transketolase; D011736:Pyridoxine