Mutation induction and mutation spectra of S. typhimurium TA100 after exposure to isohistidines.
L-Isohistidine and D,L-isohistidine, but not D-isohistidine, caused an increase of the number of mutant colonies in S. typhimurium strain TA100. Spontaneous and also sodium azide or 2-aminoanthracene induced mutant numbers were enhanced by L-isohistidine and by an isomeric mixture of D,L- and L-isohistidine. These effects could not be attributed to a growth-enhancing property. The colony probe hybridization procedure was used to investigate the effects of the histidines on the spontaneous and azide-induced spectra of the hisG46 allele in strain TA100. D,L-Isohistidine, but not the D-isomer, caused and increase of transitions (CCC-->CTC) and transversions (CCC-->CAC) in the spontaneous spectrum. Sodium azide alone induced a strong increase of CCC-->CTC transitions; combination with the D,L-isohistidine led to a further enhancement of this type of base substitutions, whereas with the L-isomer, no such effect was observed. This supports the hypothesis that the activity of D,L-isohistidine is probably not due to DNA-damaging properties, but rather to indirect mechanisms, such as enhancement of the infidelity of DNA replication and/or interference with DNA-repair or proofreading functions.
Zöhrer
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E
Institut für Tumorbiologie-Krebsforschung, Universität Wien, Austria.
Albertini
S
S
Gocke
E
E
Knasmüller
S
S
D000483:Alleles; D000873:Anthracenes / Q000633:toxicity; D001386:Azides / Q000633:toxicity; D004338:Drug Combinations; D006639:Histidine / Q000031:analogs & derivatives* / Q000633:toxicity*; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity*; D017354:Point Mutation; D012486:Salmonella typhimurium / Q000235:genetics / Q000254:growth & development; D019810:Sodium Azide
D000873:Anthracenes; D001386:Azides; D004338:Drug Combinations; D009153:Mutagens; D006639:Histidine; C006593:2-anthramine; D019810:Sodium Azide