Dai Xinhua, Hayashi Ken-ichiro, Nozaki Hiroshi, Cheng Youfa, Zhao Yunde
Section of Cell and Developmental Biology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA.
Proc Natl Acad Sci U S A. 2005 Feb 22;102(8):3129-34. doi: 10.1073/pnas.0500185102. Epub 2005 Feb 14.
The synthetic molecule sirtinol was shown previously to activate the auxin signal transduction pathway. Here we present a combination of genetic and chemical approaches to elucidate the action mechanisms of sirtinol in Arabidopsis. Analysis of sirtinol derivatives indicated that the "active moiety" of sirtinol is 2-hydroxy-1-naphthaldehyde (HNA), suggesting that sirtinol undergoes a series of transformations in Arabidopsis to generate HNA, which then is converted to 2-hydroxy-1-naphthoic acid (HNC), which activates auxin signaling. A key step in the activation of sirtinol is the conversion of HNA to HNC, which is likely catalyzed by an aldehyde oxidase. Mutations in any of the genes that are responsible for synthesizing the molybdopterin cofactor, an essential cofactor for aldehyde oxidases, led to resistance to sirtinol, probably caused by the compromised capacity of the mutants to convert HNA to HNC. We also showed that sirtinol and HNA could bypass the auxin polar transport system and that they were transported efficiently to aerial parts of seedlings, whereas HNC and 1-naphthoic acid were essentially not absorbed by Arabidopsis seedlings, suggesting that sirtinol and HNA are useful tools for auxin studies.
先前已表明合成分子西托辛醇可激活生长素信号转导途径。在此，我们采用遗传学和化学方法相结合的方式，以阐明西托辛醇在拟南芥中的作用机制。对西托辛醇衍生物的分析表明，西托辛醇的“活性部分”是2 - 羟基 - 1 - 萘甲醛（HNA），这表明西托辛醇在拟南芥中经历一系列转化生成HNA，然后HNA再转化为2 - 羟基 - 1 - 萘甲酸（HNC），后者激活生长素信号。西托辛醇激活过程中的关键步骤是HNA转化为HNC，这可能由一种醛氧化酶催化。参与合成钼蝶呤辅因子（醛氧化酶的一种必需辅因子）的任何基因发生突变，都会导致对西托辛醇产生抗性，这可能是由于突变体将HNA转化为HNC的能力受损所致。我们还表明，西托辛醇和HNA可以绕过生长素极性运输系统，并且它们能有效地运输到幼苗地上部分，而HNC和1 - 萘甲酸基本上不被拟南芥幼苗吸收，这表明西托辛醇和HNA是用于生长素研究的有用工具。
