Identification and characterization of components of a putative Petunia S-locus F-box-containing E3 ligase complex involved in S-RNase-based self-incompatibility
Identification and characterization of components of a putative Petunia S-locus F-box-containing E3 ligase complex involved in S-RNase-based self-incompatibility
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DOI：
10.1105/tpc.106.041061
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发表时间：
2006-10-01
期刊：
影响因子：
11.6
通讯作者：
Kao, Teh-hui
中科院分区：
文献类型：
--
作者：
Hua, Zhihua;Kao, Teh-hui
矮牵牛花S- locus F- box （Pi SLF）被认为在泛素介导的蛋白质降解中起着典型的F- box蛋白的作用，它与Skp1、Cullin-1和Rbx1一起组成了一个介导非自身S- RNase降解的SCF复合物。我们分离了3个P. inflata skp1 (Pi SK1， - 2和- 3)，2个Cullin- 1s （Pi CUL1- C和- G）和1个Rbx1 (Pi Rbx1) cdna，发现Pi CUL1- G不与Pi Rbx1相互作用，3个Pi skp1都不与Pi SLF2相互作用。我们还分离到一个与矮牵牛SBP1几乎相同的RING- HC蛋白，S- RNase Binding Protein1 (Pi SBP1)，它与Pi SLF、S- RNases、Pi CUL1- G和E2泛素偶联酶相互作用，表明Pi CUL1- G、SBP1和SLF可能是一种新型E3连接酶复合物的组成部分，其中Pi SBP1扮演Skp1和Rbx1的角色。S- RNases与非自生Pi SLFs的相互作用大于与自生Pi SLFs的相互作用，而Pi SLFs与非自生S- RNases的相互作用也大于与自生S- RNases的相互作用。细菌表达的S-1-、S-2-和S-3-核糖核酸酶在无细胞系统中被26S蛋白酶体途径降解，尽管不是以S等位基因特异性的方式降解。原生糖基化S3- RNase没有显著降解；然而，去糖基化的S-3- RNase的降解效率与细菌表达的S- RNase一样高。最后，S- rnase在花粉管提取物中泛素化，但这是否由含有E3复合物的Pi SLF介导尚不清楚。
Petunia inflata S- locus F- box ( Pi SLF) is thought to function as a typical F- box protein in ubiquitin- mediated protein degradation and, along with Skp1, Cullin-1, and Rbx1, could compose an SCF complex mediating the degradation of nonself S- RNase but not self S- RNase. We isolated three P. inflata Skp1s ( Pi SK1, - 2, and - 3), two Cullin- 1s ( Pi CUL1- C and - G), and an Rbx1 ( Pi RBX1) cDNAs and found that Pi CUL1- G did not interact with Pi RBX1 and that none of the three Pi SKs interacted with Pi SLF2. We also isolated a RING- HC protein, S- RNase Binding Protein1 ( Pi SBP1), almost identical to Petunia hybrida SBP1, which interacts with Pi SLFs, S- RNases, Pi CUL1- G, and an E2 ubiquitin- conjugating enzyme, suggesting that Pi CUL1- G, SBP1, and SLF may be components of a novel E3 ligase complex, with Pi SBP1 playing the roles of Skp1 and Rbx1. S- RNases interact more with nonself Pi SLFs than with self Pi SLFs, and Pi SLFs also interact more with nonself S- RNases than with self S- RNases. Bacterially expressed S-1-, S-2-, and S-3- RNases are degraded by the 26S proteasomal pathway in a cell-free system, albeit not in an S- allele - specific manner. Native glycosylated S3- RNase is not degraded to any significant extent; however, deglycosylated S-3- RNase is degraded as efficiently as the bacterially expressed S- RNases. Finally, S- RNases are ubiquitinated in pollen tube extracts, but whether this is mediated by the Pi SLF containing E3 complex is unknown.