Auxin-transporting ABC transporters are defined by a conserved D/E-P motif regulated by a prolylisomerase
Auxin-transporting ABC transporters are defined by a conserved D/E-P motif regulated by a prolylisomerase
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DOI：
10.1074/jbc.ra120.014104
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发表时间：
2020-09-11
影响因子：
4.8
通讯作者：
Geisler, Markus
中科院分区：
文献类型：
--
作者：
Hao, Pengchao;Xia, Jian;Geisler, Markus
植物激素生长素必须以细胞到细胞的方式在植物中运输，才能影响其各种生理功能。ABCB转运蛋白对生长素的这种极性分布是至关重要的，但控制其功能的调控机制尚不完全清楚。ABCB1的生长素转运活性被认为是通过与FKBP42/Twisted Dwarf1(TWD1)的物理相互作用来调节的，但TWD1证明这种PPIase活性的尝试到目前为止都失败了。通过基于结构的方法，我们在拟南芥ABCB1的核苷酸结合域和连接子中发现了几个暴露在表面的Pro残基，这些突变不会改变ABCB1蛋白的稳定性或位置，但确实会影响其转运活性。P1008是保守的D/E-P基序的一部分，该基序似乎是生长素运输ABCB的特异性基序，我们现在称之为ATA。酸性残基的突变也取消了ABCB1的生长素运输活性。所有已被确证为生长素运输的高等植物ABCB都带有这个保守的基序，强调了它的预测潜力。将这个D/E-P基序引入到苹果酸进口体ABCB14中，增加了其苹果酸及其背景生长素的运输活性，表明该基序对运输能力有影响。D/E-P1008基序在ABCB1-TWD1相互作用和TWD1激活ABCB1介导的生长素运输中也是重要的。综上所述，我们的数据暗示了TWD1作为ABCB介导的生长素运输的推定激活剂的新功能，它通过肽基-脯氨酸键的顺式转移。
The plant hormone auxin must be transported throughout plants in a cell-to-cell manner to affect its various physiological functions. ABCB transporters are critical for this polar auxin distribution, but the regulatory mechanisms controlling their function is not fully understood. The auxin transport activity of ABCB1 was suggested to be regulated by a physical interaction with FKBP42/Twisted Dwarf1 (TWD1), a peptidylprolylcis-transisomerase (PPIase), but all attempts to demonstrate such a PPIase activity by TWD1 have failed so far. By using a structure-based approach, we identified several surface-exposed proline residues in the nucleotide binding domain and linker of Arabidopsis ABCB1, mutations of which do not alter ABCB1 protein stability or location but do affect its transport activity. P1008 is part of a conserved signature D/E-P motif that seems to be specific forauxin-transportingABCBs, which we now refer to as ATAs. Mutation of the acidic residue also abolishes auxin transport activity by ABCB1. All higher plant ABCBs for which auxin transport has been conclusively proven carry this conserved motif, underlining its predictive potential. Introduction of this D/E-P motif into malate importer, ABCB14, increases both its malate and its background auxin transport activity, suggesting that this motif has an impact on transport capacity. The D/E-P1008 motif is also important for ABCB1-TWD1 interactions and activation of ABCB1-mediated auxin transport by TWD1. In summary, our data imply a new function for TWD1 acting as a putative activator of ABCB-mediated auxin transport bycis-transisomerization of peptidyl-prolyl bonds.