Abstract：
In eukaryotes, EPSINs are Epsin N-terminal Homology (ENTH) domain-containing proteins that serve as monomeric clathrin adaptors at the plasma membrane (PM) or the trans-Golgi Network (TGN)/early endosomes (EE). The model plant Arabidopsis thaliana encodes for seven ENTH proteins, of which so far, only AtEPSIN1 (AtEPS1) and MODIFIED TRANSPORT TO THE VACUOLE1 (AtMTV1) localize to the TGN/EE and contribute to cargo trafficking to both the cell surface and the vacuole. However, relatively little is known about role(s) of any plant EPSIN in governing physiological responses. We have recently shown that AtEPS1 is a positive modulator of plant immune signaling and pattern-triggered immunity against flagellated Pseudomonas syringae pv. tomato (Pto) DC3000 bacteria. In eps1 mutants, impaired immune responses correlate with reduced accumulation of the receptor FLAGELLIN SENSING2 (AtFLS2) and the convergent immune co-receptor BRASSINOSTEROID INSENTIVE1-ASSOCIATED RECEPTOR KINASE1 (AtBAK1) in the PM. Here, we report that in contrast to AtEPS1, the TGN/EE-localized AtMTV1 did not contribute significantly to immunity against pathogenic Pto DC3000 bacteria. We also compared the amino acid sequences, peptide motif structures and in silico tertiary structures of the ENTH domains of AtEPS1 and AtMTV1 in more detail. We conclude that despite sharing the classical tertiary alpha helical ENTH-domain structure and clathrin-binding motifs, the overall low amino acid identity and differences in peptide motifs may explain their role(s) in trafficking of some of the same as well as distinct cargo components to their site of function, with the latter potentially contributing to differences in physiological responses.
摘要：
在真核生物中,EPSIN是包含EpsinN末端同源性（ENTH）结构域的蛋白质，可在质膜（PM）或反式高尔基体网络（TGN）/早期内体（EE）上用作单体网格蛋白衔接子。模式植物拟南芥编码七种ENTH蛋白，到目前为止，只有AtEPSIN1（AtEPS1）和改进型VACUOLE1（AtMTV1）定位到TGN/EE，并有助于向细胞表面和液泡运输货物。然而,对任何植物EPSIN在控制生理反应中的作用知之甚少。我们最近表明，AtEPS1是植物免疫信号和模式触发的针对鞭毛丁香假单胞菌pv的免疫的阳性调节剂。番茄（Pto）DC3000细菌。在eps1突变体中，受损的免疫应答与PM中受体FLAGELLINSENSING2（AtFLS2）和会聚性免疫共受体胆碱酯酶敏感性相关的受体激酶1（AtBAK1）的积累减少相关。这里,我们报道,与AtEPS1相比,TGN/EE定位的AtMTV1对针对致病性PtoDC3000细菌的免疫没有显著贡献.我们还比较了氨基酸序列，更详细地介绍了AtEPS1和AtMTV1的ENTH结构域的肽基序结构和计算机上的三级结构。我们得出的结论是，尽管共享经典的三级α螺旋ENTH结构域结构和网格蛋白结合基序，总体的低氨基酸同一性和肽基序的差异可以解释它们在将一些相同的以及不同的货物成分贩运到其功能位点中的作用，后者可能导致生理反应的差异。
