title: A tryptophan auxotroph of Hyoscyamus muticus lacking tryptophan-synthase activity.
abstract: A variant clone of Hyoscyamus muticus (VIIIB9) with a specific, stable requirement for tryptophan has been shown to have the following characteristics: (i) no accumulation of tryptophan from anthranilic acid; (ii) growth on added tryptophan or indole but not on anthranilic acid; (iii) accumulation of indole-3-glycerol phosphate and other indole derivatives; (iv) extractable activity of the enzymes for tryptophan biosynthesis, including the partial reaction 2 of tryptophan synthase but not reactions 1 or 3. Thus these data provide in-vivo evidence for the existence of a two-component, bacterial-type tryptophan synthase in plants, the tryptophan auxotrophy of VIIIB9 probably being the consequence of a mutation in the α-subunit of the tryptophan-synthase complex.
authors.affiliation: Friedrich Miescher-Institut, Postfach 2543, CH-4002, Basel, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Fankhauser
authors.forename: F
authors.initials: F
authors.lastname: Pythoud
authors.forename: P J
authors.initials: PJ
authors.lastname: King