Evidence for a SAL1-PAP Chloroplast Retrograde Pathway That Functions in Drought and High Light Signaling in Arabidopsis
Evidence for a SAL1-PAP Chloroplast Retrograde Pathway That Functions in Drought and High Light Signaling in Arabidopsis
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DOI：
10.1105/tpc.111.091033
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发表时间：
2011-11-01
期刊：
影响因子：
11.6
通讯作者：
Pogson, Barry J.
中科院分区：
文献类型：
--
作者：
Estavillo, Gonzalo M.;Crisp, Peter A.;Pogson, Barry J.
真核细胞的区隔需要一系列复杂的亚细胞信息，包括从叶绿体和线粒体到细胞核的多个逆行信号，以调节基因表达。在这里，我们提出其中一个这样的信号是磷酸核苷酸(3‘-磷酸腺苷5’-磷酸[PAP])，它在干旱和强光(HL)胁迫下在拟南芥中积累，SAL1酶通过将PAP去磷酸化为AMP来调节其水平。SAL1在叶绿体和线粒体中积累，但不在细胞质中积累。Sal1突变体在没有明显改变肌醇磷酸水平的情况下积累了20倍以上的PAP，表明PAP是体内的主要底物。值得注意的是，将SAL1转基因靶向于sal1突变体的核或叶绿体，降低了总PAP水平和HL诱导的抗坏血酸PEROXIDASE 2基因的表达。这表明PAP必须能够在蜂窝舱之间移动。PAP的作用方式可能是抑制5‘-3’外切核糖核酸酶(XRN)，因为SAL1和核XRN调控类似的HL和干旱诱导基因亚群的表达，SAL1突变体积累XRN底物，PAP抑制酵母(Saccharmyces Cerevisiae)XRN。我们提出了一个SAL1-PAP逆行途径，可以在HL和干旱胁迫下改变核基因的表达。
Compartmentation of the eukaryotic cell requires a complex set of subcellular messages, including multiple retrograde signals from the chloroplast and mitochondria to the nucleus, to regulate gene expression. Here, we propose that one such signal is a phosphonucleotide (3'-phosphoadenosine 5'-phosphate [PAP]), which accumulates in Arabidopsis thaliana in response to drought and high light (HL) stress and that the enzyme SAL1 regulates its levels by dephosphorylating PAP to AMP. SAL1 accumulates in chloroplasts and mitochondria but not in the cytosol. sal1 mutants accumulate 20-fold more PAP without a marked change in inositol phosphate levels, demonstrating that PAP is a primary in vivo substrate. Significantly, transgenic targeting of SAL1 to either the nucleus or chloroplast of sal1 mutants lowers the total PAP levels and expression of the HL-inducible ASCORBATE PEROXIDASE2 gene. This indicates that PAP must be able to move between cellular compartments. The mode of action for PAP could be inhibition of 5' to 3' exoribonucleases (XRNs), as SAL1 and the nuclear XRNs modulate the expression of a similar subset of HL and drought-inducible genes, sal1 mutants accumulate XRN substrates, and PAP can inhibit yeast (Saccharomyces cerevisiae) XRNs. We propose a SAL1-PAP retrograde pathway that can alter nuclear gene expression during HL and drought stress.