Production of 3-nitrosoindole derivatives by Escherichia coli during anaerobic growth.
When Escherichia coli K-12 is grown anaerobically in medium containing tryptophan and sodium nitrate, it produces red compounds. The reaction requires functional genes for trytophanase (tnaA), a tryptophan permease (tnaB), and a nitrate reductase (narG), as well as a natural drop in the pH of the culture. Mass spectrometry revealed that the purified chromophores had mass/charge ratios that closely match those for indole red, indoxyl red, and an indole trimer. These compounds are known products of chemical reactions between indole and nitrous acid. They are derived from an initial reaction of 3-nitrosoindole with indole. Apparently, nitrite that is produced from the metabolic reduction of nitrate is converted in the acid medium to nitrous acid, which leads to the nitrosation of the indole that is generated by tryptophanase. An nfi (endonuclease V) mutant and a recA mutant were selectively killed during the period of chromophore production, and a uvrA strain displayed reduced growth. These effects depended on the addition of nitrate to the medium and on tryptophanase activity in the cells. Unexpectedly, the killing of a tnaA(+) nfi mutant was not accompanied by marked increases in mutation frequencies for several traits tested. The vulnerability of three DNA repair mutants indicates that a nitrosoindole or a derivative of a nitrosoindole produces lethal DNA damage.
Kwon
Young-Man
YM
Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia 30322, USA.
Weiss
Bernard
B
D026905:Amino Acid Transport Systems / Q000378:metabolism; D000693:Anaerobiosis; D015169:Colony Count, Microbial; D048168:Escherichia coli K12 / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism; D007211:Indoles / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D050296:Microbial Viability; D050901:Nitrate Reductase / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009608:Nitrous Acid / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism; D014368:Tryptophanase / Q000378:metabolism
D026905:Amino Acid Transport Systems; D029968:Escherichia coli Proteins; D007211:Indoles; D009566:Nitrates; D009573:Nitrites; C581838:indoxyl red; C035131:TnaB protein, E coli; D014364:Tryptophan; C031618:sodium nitrate; C508365:NarG protein, E coli; D050901:Nitrate Reductase; D014368:Tryptophanase; D009608:Nitrous Acid