title: Isolation of a cDNA for tryptophan synthase beta from rice and studies of its expression in a 5-methyltryptophan-resistant mutant of rice.
abstract: A cDNA clone encoding rice tryptophan synthase beta (TSB) was isolated and its transcript level was examined in TR-No. 73, a derivative of a previously isolated rice mutant (TR-1) that is resistant to 5-methyltryptophan. The cDNA sequence of the rice gene for TSB was very similar to that of genes for TSB from other plants. Northern blotting analysis revealed that the steady-state level of TSB mRNA in the 5MT-resistant mutant TR-No. 73 was 1.3 times higher than the level of TSB mRNA in control rice plants under standard conditions. The level of TSB mRNA in control rice plants decreased after treatment of plants with 5MT. Similarly, the level of TSB mRNA in TR-No. 73 initially decreased, although less so than in control rice. However, after 12 h of treatment with 5MT, the level of the transcript in TR-No. 73 returned to the level under standard conditions. The activity of tryptophan synthase (TS) in seedlings of TR-No. 73 was about 2.3 times higher than that in seedlings of control rice under standard conditions.
authors.affiliation: Institute of Genetic Ecology, Tohoku University, Sendai, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kisaka
authors.forename: M
authors.initials: M
authors.lastname: Kisaka
authors.forename: H Y
authors.initials: HY
authors.lastname: Lee
authors.forename: T
authors.initials: T
authors.lastname: Kameya
mesh_terms: D000595:Amino Acid Sequence; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification*; D004351:Drug Resistance; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D010944:Plants / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000494:pharmacology; D014367:Tryptophan Synthase / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; C004182:5-methyltryptophan; D014364:Tryptophan; D014367:Tryptophan Synthase