Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México. Cd. Mx, 04510, México.
Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México. Cd. Mx, 04510, México.
Plant J. 2020 Aug;103(4):1304-1317. doi: 10.1111/tpj.14802. Epub 2020 Jun 13.
In self-incompatible Solanaceae, the pistil protein S-RNase contributes to S-specific pollen rejection in conspecific crosses, as well as to rejecting pollen from foreign species or whole clades. However, S-RNase alone is not sufficient for either type of pollen rejection. We describe a thioredoxin (Trx) type h from Nicotiana alata, NaTrxh, which interacts with and reduces S-RNase in vitro. Here, we show that expressing a redox-inactive mutant, NaTrxh , suppresses both S-specific pollen rejection and rejection of pollen from Nicotiana plumbaginifolia. Biochemical experiments provide evidence that NaTrxh specifically reduces the Cys -Cys disulphide bond of S -Rnase, resulting in a significant increase of its ribonuclease activity. This reduction and increase in S-RNase activity by NaTrxh helps to explain why S-RNase alone could be insufficient for pollen rejection.
在自交不亲和的茄科植物中，柱头蛋白 S-RNase 有助于同种杂交中 S 特异性花粉的排斥，以及对外来物种或整个进化枝花粉的排斥。然而，S-RNase 本身不足以进行这两种类型的花粉排斥。我们描述了来自 Nicotiana alata 的一种硫氧还蛋白 (Trx) 型 h，即 NaTrxh，它与 S-RNase 在体外相互作用并使其还原。在这里，我们表明表达一种氧化还原失活突变体，NaTrxh ，可同时抑制 S 特异性花粉排斥和 Nicotiana plumbaginifolia 花粉的排斥。生化实验提供的证据表明，NaTrxh 特异性地还原 S-RNase 的 Cys-Cys 二硫键，导致其核糖核酸酶活性显著增加。NaTrxh 对 S-RNase 活性的这种降低和增加有助于解释为什么 S-RNase 本身不足以进行花粉排斥。
