Mutations in circularly permuted GTPase family genes AtNOA1/RIF1/SVR10 and BPG2 suppress var2-mediated leaf variegation in Arabidopsis thaliana
Mutations in circularly permuted GTPase family genes AtNOA1/RIF1/SVR10 and BPG2 suppress var2-mediated leaf variegation in Arabidopsis thaliana
复制标题
拟南芥中循环排列的 GTPase 家族基因 AtNOA1/RIF1/SVR10 和 BPG2 的突变抑制 var2 介导的叶片杂色
DOI：
10.1007/s11120-015-0195-9
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发表时间：
2016-03-01
影响因子：
3.7
通讯作者：
Yu, Fei
中科院分区：
文献类型：
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作者：
Qi, Yafei;Zhao, Jun;Yu, Fei
叶片杂变突变体是一类独特的叶绿体发育突变体，是研究叶绿体发育调控的理想遗传材料。利用拟南芥黄杂变（var2）突变体和基因抑制因子分析，探讨了拟南芥叶绿体发育的机制。在这里，我们报道了一个新的var2抑制基因座抑制基因（SVR10）的分离。遗传定位和分子互补表明，SVR10编码一种循环排列的GTPase，该酶被报道为拟南芥一氧化氮相关酶1 (AtNOA1)，可抵抗FOSMIDOMYCIN 1 （RIF1）的抑制。生化证据表明SVR10/AtNOA1/RIF1可能定位于叶绿体基质。研究人员进一步证实，SVR10/AtNOA1/RIF1的同源突变体BRASSINAZOLE INSENSITIVE PALE GREEN 2 （BPG2）也能抑制var2叶片斑纹。突变体SVR10和BPG2的光合作用和叶绿体蛋白质的积累受到损害。有趣的是，二维蓝色天然凝胶分析显示，SVR10和BPG2突变体在类囊体膜复合物的组装上存在缺陷，包括主要光合复合物水平降低和含有叶绿素-蛋白超复合物的光系统异常积累。综上所述，我们的研究结果表明，SVR10和BPG2在功能上与VAR2相关，可能通过它们在调节叶绿体蛋白稳态中的潜在作用。SVR10和BPG2都是有效的类囊体蛋白复合物组装和光合作用所必需的。
Leaf variegation mutants constitute a unique group of chloroplast development mutants and are ideal genetic materials to dissect the regulation of chloroplast development. We have utilized the Arabidopsis yellow variegated (var2) mutant and genetic suppressor analysis to probe the mechanisms of chloroplast development. Here we report the isolation of a new var2 suppressor locus SUPPRESSOR OF VARIEGATION (SVR10). Genetic mapping and molecular complementation indicated that SVR10 encodes a circularly permuted GTPase that has been reported as Arabidopsis thaliana NITRIC OXIDE ASSOCIATED 1 (AtNOA1) and RESISTANT TO INHIBITION BY FOSMIDOMYCIN 1 (RIF1). Biochemical evidence showed that SVR10/AtNOA1/RIF1 likely localizes to the chloroplast stroma. We further demonstrate that the mutant of a close homologue of SVR10/AtNOA1/RIF1, BRASSINAZOLE INSENSITIVE PALE GREEN 2 (BPG2), can also suppress var2 leaf variegation. Mutants of SVR10 and BPG2 are impaired in photosynthesis and the accumulation of chloroplast proteins. Interestingly, two-dimensional blue native gel analysis showed that mutants of SVR10 and BPG2 display defects in the assembly of thylakoid membrane complexes including reduced levels of major photosynthetic complexes and the abnormal accumulation of a chlorophyll-protein supercomplex containing photosystem I. Taken together, our findings suggest that SVR10 and BPG2 are functionally related with VAR2, likely through their potential roles in regulating chloroplast protein homeostasis, and both SVR10 and BPG2 are required for efficient thylakoid protein complex assembly and photosynthesis.