Rapid accumulation of intracellular 2-keto-3-deoxy-6-phosphogluconate in an Entner-Doudoroff aldolase mutant results in bacteriostasis.
The accumulation of 2-keto-3-deoxy-6-phosphogluconate, the key intermediate of the Entner-Doudoroff pathway, has long been thought to inhibit growth of bacteria, but careful measurements of 2-keto-3-deoxy-6-phosphogluconate accumulation by growing cells and the correlation of intracellular 2-keto-3-deoxy-6-phosphogluconate levels to growth inhibition had not been made. A system designed for this purpose was developed in Escherichia coli strains, allowing 2-keto-3-deoxy-6-phosphogluconate accumulation to be experimentally induced and measured by extraction of the cell pool. Addition of gluconate to a strain which lacked 2-keto-3-deoxy-6-phosphogluconate aldolase and overproduced 6-phosphogluconate dehydratase resulted in an increase in the intracellular concentration of 2-keto-3-deoxy-6-phosphogluconate from undetectable levels to 2.0 mM within 15 s, as measured by anion-exchange HPLC. The accumulation of 2-keto-3-deoxy-6-phosphogluconate was correlated with an immediate and significant decrease in growth; this inhibition was determined to be bacteriostatic and not bactericidal. It had been proposed that the mechanism of 2-keto-3-deoxy-6-phosphogluconate toxicity involves competitive inhibition of 6-phosphogluconate dehydrogenase and the consequent block of the pentose phosphate pathway. An experiment addressing this hypothesis failed to provide any supporting data.
Fuhrman
L K
LK
Department of Microbiology, Ohio State University, Columbus 43210-1292, USA.
Wanken
A
A
Nickerson
K W
KW
Conway
T
T
D000446:Aldehyde-Lyases / Q000502:physiology*; D004926:Escherichia coli / Q000502:physiology*; D005942:Gluconates / Q000378:metabolism*; D009154:Mutation; D010427:Pentose Phosphate Pathway; D010734:Phosphogluconate Dehydrogenase / Q000037:antagonists & inhibitors
D005942:Gluconates; D010734:Phosphogluconate Dehydrogenase; D000446:Aldehyde-Lyases; C100131:phospho-2-keto-3-deoxy-gluconate aldolase