PDF(Pubmed)
Abstract：
Calcium-mediated signaling pathways are known to play important roles in the polar growth of pollen tubes. The calcium-dependent protein kinase, PiCDPK1, has been shown to be involved in regulating this process through interaction with a guanine dissociation inhibitor, PiRhoGDI1. To more fully understand the role of PiCDPK1 in pollen tube extension, we designed a pull-down study to identify additional substrates of this kinase. These experiments identified 123 putative interactors. Two of the identified proteins were predicted to directly interact with PiCDPK1, and this possibility was investigated in planta. The first, NtGF14, a 14-3-3-like protein, did not produce a noticeable phenotype when overexpressed in pollen alone but partially rescued the spherical tube phenotype caused by PiCDPK1 over-expression when co-over-expressed with the kinase. The second, NtREN1, a GTPase activating protein (GAP), severely inhibited pollen tube germination when over-expressed, and its co-over-expression with PiCDPK1 did not substantially affect this phenotype. These results suggest a novel in vivo interaction between NtGF14 and PiCDPK1 but do not support the direct interaction between PiCDPK1 and NtREN1. We demonstrate the utility of the methodology used to identify potential protein interactions while confirming the necessity of additional studies to confirm their validity. Finally, additional support was found for intersection between PiCDPK1 and RopGTPase pathways to control polar growth at the pollen tube tip.
摘要：
已知钙介导的信号通路在花粉管的极性生长中起重要作用。钙依赖性蛋白激酶，PiCDPK1已被证明通过与鸟嘌呤解离抑制剂的相互作用参与调节这一过程。PiRhoGDI1.为了更全面地了解PiCDPK1在花粉管延长中的作用,我们设计了一项下拉研究来鉴定该激酶的其他底物.这些实验确定了123个推定的相互作用者。预测两种鉴定的蛋白质直接与PiCDPK1相互作用，并在植物中研究了这种可能性。第一,NtGF14，一种14-3-3样蛋白，当单独在花粉中过表达时，不会产生明显的表型，但当与激酶共过表达时，部分挽救了由PiCDPK1过表达引起的球形管表型。第二个,NtREN1，一种GTP酶激活蛋白（GAP），过度表达严重抑制花粉管萌发，并且其与PiCDPK1的共过表达对该表型没有实质性影响。这些结果表明NtGF14和PiCDPK1之间的新的体内相互作用,但不支持PiCDPK1和NtREN1之间的直接相互作用。我们证明了用于识别潜在蛋白质相互作用的方法的实用性，同时确认了进一步研究以确认其有效性的必要性。最后,发现了PiCDPK1和RopGTP酶途径之间的交叉以控制花粉管尖端的极性生长的额外支持。
