Department of Agronomy, University of Illinois, Urbana, Illinois 61801.
Plant Physiol. 1981 Jun;67(6):1101-4. doi: 10.1104/pp.67.6.1101.
Twenty-three indole analogs were used to inhibit the growth of carrot and tobacco suspension cultures. The addition of tryptophan or indole partially reversed the inhibition of both cell lines only for 4-fluoroindole, 5-fluoroindole, and 6-fluoroindole. Inhibition of tobacco cell growth by 5-aminoindole, 5-methoxyindole, 6-methoxyindole, or 7-methoxyindole was also partially reversed. Previously selected carrot and tobacco lines, which have high free tryptophan levels, grew in the presence of the analogs for which reversal was noted in all cases except 5-aminoindole and also in some other cases. Growth inhibition caused by all 10 tryptophan analogs studied was partially reversible by tryptophan or indole and the high tryptophan lines were also able to grow in the presence of concentrations inhibitory to the wild type lines.Tryptophan synthase activity from both species could utilize most of the 2 or 3 position unsubstituted indole analogs to produce the corresponding tryptophan analogs. Using carrot cell extracts, the identity of the correct product was confirmed by automated amino acid analysis for 4-fluoroindole, 5-fluoroindole, and 5-hydroxyindole. The analogs most rapidly utilized by carrot tryptophan synthase were 6-methoxyindole and the 4-, 5-, or 6-fluoroindoles. When 4-fluoroindole, 5-hydroxyindole, 5-methoxyindole, or 5-methylindole were incubated with carrot cells the corresponding tryptophan analog was formed in all cases as identified by amino acid analysis.These results indicate that cultured carrot and tobacco cells can convert certain nontoxic indole analogs into toxic tryptophan analogs. Using 5-fluoroindole and 6-fluoroindole, attempts were made to isolate tryptophan auxotrophs lacking tryptophan synthase from diploid carrot and tobacco lines. However, only 5-methyltryptophan-resistant lines, which presumably accumulate high levels of free tryptophan, were recovered.
二十三种吲哚类似物被用来抑制胡萝卜和烟草悬浮培养物的生长。只有对于 4-氟吲哚、5-氟吲哚和 6-氟吲哚，色氨酸或吲哚的添加部分逆转了这两种细胞系的抑制作用。5-氨基吲哚、5-甲氧基吲哚、6-甲氧基吲哚或 7-甲氧基吲哚对烟草细胞生长的抑制作用也部分逆转。先前选择的胡萝卜和烟草系，其游离色氨酸水平较高，在所有情况下（除 5-氨基吲哚外），以及在其他一些情况下，都能在这些类似物存在的情况下生长，而这些类似物的逆转作用都被注意到了。所有 10 种研究的色氨酸类似物引起的生长抑制作用，通过色氨酸或吲哚部分可逆，高色氨酸系也能够在对野生型系有抑制作用的浓度下生长。来自这两个物种的色氨酸合酶活性都可以利用大部分 2 位或 3 位未取代的吲哚类似物来产生相应的色氨酸类似物。使用胡萝卜细胞提取物，通过自动氨基酸分析，在 4-氟吲哚、5-氟吲哚和 5-羟基吲哚的情况下，确认了正确产物的身份。胡萝卜色氨酸合酶利用最快的类似物是 6-甲氧基吲哚和 4-、5-或 6-氟吲哚。当 4-氟吲哚、5-羟基吲哚、5-甲氧基吲哚或 5-甲基吲哚与胡萝卜细胞孵育时，在所有情况下都形成了相应的色氨酸类似物，如氨基酸分析所确定的。这些结果表明，培养的胡萝卜和烟草细胞可以将某些无毒的吲哚类似物转化为有毒的色氨酸类似物。使用 5-氟吲哚和 6-氟吲哚，试图从二倍体胡萝卜和烟草系中分离缺乏色氨酸合酶的色氨酸营养缺陷型。然而，只有 5-甲基色氨酸抗性系被回收，这可能是由于积累了高水平的游离色氨酸。
