title: Characterization of tryptophan synthase alpha subunit mutants of Arabidopsis thaliana.
abstract: Three mutations in the Arabidopsis thaliana gene encoding the alpha subunit of tryptophan synthase were isolated by selection for resistance to 5-methylanthranilate or 5-fluoroindole, toxic analogs of tryptophan pathway intermediates. Plants homozygous for trp3-1 and trp3-2 are light-conditional tryptophan auxotrophs, while trp3-100 is a more leaky mutant. Genetic complementation crosses demonstrated that the three mutations are allelic to each other, and define a new complementation group. All three mutants have decreased steady-state levels of tryptophan synthase alpha protein, and the trp3-100 polypeptide exhibits altered electrophoretic mobility. All three mutations were shown to be in the TSA1 (tryptophan synthase alpha subunit) structural gene by several criteria. Firstly, the trp3-1 mutation is linked to TSA1 on the bottom of chromosome 3. Secondly, the trp3-1 mutation was complemented when transformed with the wild-type TSA1 gene. Finally, DNA sequence analysis of the TSA1 gene revealed a single transition mutation in each trp3 mutant.
authors.affiliation: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY 14853-1801, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Radwanski
authors.forename: A J
authors.initials: AJ
authors.lastname: Barczak
authors.forename: R L
authors.initials: RL
authors.lastname: Last
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D002874:Chromosome Mapping; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics; D014367:Tryptophan Synthase / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014367:Tryptophan Synthase