Hervieu F, Vaucheret H
Laboratoire de Biologie Cellulaire, INRA, Versailles, France.
Mol Gen Genet. 1996 May 23;251(2):220-4. doi: 10.1007/BF02172921.
The metabolic control of branches chain amino acid (BCAA) biosynthesis involves allosteric regulation of acetolactate synthase (ALS) by the end-products of the pathway, valine, leucine and isoleucine. We describe here the molecular basis of valine resistance. We cloned and sequenced an ALS gene from the tobacco mutant Valr-1 and found a single basepair substitution relative to the wild-type allele. This mutation causes a serine to leucine change in the amino acid sequence of ALS at position 214. We then mutagenized the wild-type allele of the ALS gene of Arabidopsis and found that it confers valine resistance when introduced into tobacco plants. Taken together, these results suggest that the serine to leucine change at position 214 of ALS is responsible for valine resistance in tobacco.
支链氨基酸（BCAA）生物合成的代谢控制涉及该途径的终产物缬氨酸、亮氨酸和异亮氨酸对乙酰乳酸合酶（ALS）的变构调节。我们在此描述缬氨酸抗性的分子基础。我们从烟草突变体Valr-1中克隆并测序了一个ALS基因，发现相对于野生型等位基因有一个单碱基对替换。该突变导致ALS氨基酸序列第214位的丝氨酸变为亮氨酸。然后我们对拟南芥ALS基因的野生型等位基因进行诱变，发现将其导入烟草植株时可赋予缬氨酸抗性。综合这些结果表明，ALS第214位的丝氨酸到亮氨酸的变化是烟草中缬氨酸抗性的原因。
