Arabidopsis Bax inhibitor-1 interacts with enzymes related to very-long-chain fatty acid synthesis
Arabidopsis Bax inhibitor-1 interacts with enzymes related to very-long-chain fatty acid synthesis
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DOI：
10.1007/s10265-018-01081-8
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发表时间：
2019-01
影响因子：
2.8
通讯作者：
M. Nagano;Chika Kakuta;Y. Fukao;Masayuki Fujiwara;H. Uchimiya;M. Kawai‐Yamada
中科院分区：
文献类型：
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作者：
M. Nagano;Chika Kakuta;Y. Fukao;Masayuki Fujiwara;H. Uchimiya;M. Kawai‐Yamada
Bax抑制剂-1（BI-1）是一种广泛保守的细胞死亡调节因子，在植物中赋予对环境胁迫的抗性。先前的研究表明拟南芥BI-1（AtBI-1）通过与电子传递蛋白细胞色素b 5（AtCb 5）相互作用来修饰鞘脂。为了揭示AtBI-1如何调节鞘脂的合成，我们筛选了酵母鞘脂缺陷突变体，并确定了AtBI-1功能所必需的新型酶-酵母β 2和β 3。β 2和β 3是合成极长链脂肪酸（VLCFA）的缩合酶，极长链脂肪酸是植物鞘脂中的主要脂肪酸。在拟南芥中，我们确定了四个ELO同源物（AtB 1-AtB 4），定位于内质网膜。在这些AtCbs中，AtCbs 1和AtCbs 2具有特征性的组氨酸基序，并与AtCb 5-B结合。该结果表明AtBI-1通过AtCb 5与AtB 1和AtB 2相互作用。AtCb 2和AtCb 5-B还与VLCFA合成所必需的KCR 1、PAS 2和CER 10相互作用。因此，AtCb 2可能与AtCb 5一起参与拟南芥VLCFA的合成。此外，我们的免疫共沉淀/质谱分析表明，AtBI-1与AtB 2，KCR 1，PAS 2，CER 10和AtCb 5-D形成复合物。此外，AtBI-1有助于响应氧化应激快速合成2-羟基化VLCFA。这些结果表明AtBI-1通过与VLCFA合成酶相互作用来调节VLCFA合成。
Bax inhibitor-1 (BI-1) is a widely conserved cell death regulator that confers resistance to environmental stress in plants. Previous studies suggest thatArabidopsis thalianaBI-1 (AtBI-1) modifies sphingolipids by interacting with cytochromeb5(AtCb5), an electron-transfer protein. To reveal how AtBI-1 regulates sphingolipid synthesis, we screened yeast sphingolipid-deficient mutants and identified yeast ELO2 and ELO3 as novel enzymes that are essential for AtBI-1 function. ELO2 and ELO3 are condensing enzymes that synthesize very-long-chain fatty acids (VLCFAs), major fatty acids in plant sphingolipids. In Arabidopsis, we identified four ELO homologs (AtELO1–AtELO4), localized in the endoplasmic reticulum membrane. Of those AtELOs, AtELO1 and AtELO2 had a characteristic histidine motif and were bound to AtCb5-B. This result suggests that AtBI-1 interacts with AtELO1 and AtELO2 through AtCb5. AtELO2 and AtCb5-B also interact with KCR1, PAS2, and CER10, which are essential for the synthesis of VLCFAs. Therefore, AtELO2 may participate in VLCFA synthesis with AtCb5 in Arabidopsis. In addition, our co-immunoprecipitation/mass spectrometry analysis demonstrated that AtBI-1 forms a complex with AtELO2, KCR1, PAS2, CER10, and AtCb5-D. Furthermore, AtBI-1 contributes to the rapid synthesis of 2-hydroxylated VLCFAs in response to oxidative stress. These results indicate that AtBI-1 regulates VLCFA synthesis by interacting with VLCFA-synthesizing enzymes.