郁飞、齐亚飞等《New Phytologist》2023年

论文题目：Interaction of PALE CRESS with PAP2/pTAC2 and PAP3/pTAC10 affects the accumulation of plastid-encoded RNA polymerase complexes in Arabidopsis

论文作者：Xiaomin Wang (王晓敏)1, Yafei Qi(齐亚飞)1, Na Liu (刘娜), Qiaoxin Zhang (张侨欣), Sha Xie (谢莎), Yang Lei (雷洋), Bilang Li (李碧浪), Jingxia Shao (邵景侠), Fei Yu (郁飞) *, Xiayan Liu (刘夏燕) *

论文摘要：The transcription of photosynthesis genes in chloroplasts is largely mediated by the plastid-encoded RNA polymerase (PEP), which resembles prokaryotic-type RNA polymerases, but with plant-specific accessory subunits known as plastid transcriptionally active chromosome proteins (pTACs) or PEP-associated proteins (PAPs). However, whether additional factors are involved in the biogenesis of PEP complexes remains unknown. Here, we investigated the function of an essential gene, PALE CRESS (PAC), in the accumulation of PEP complexes in chloroplasts. We established that an Arabidopsis leaf variegation mutant, variegated 6-1 (var6-1), is a hypomorphic allele of PAC. Unexpectedly, we revealed that a fraction of VAR6/PAC is associated with thylakoid membranes, where it interacts with PEP complexes. Additionally, we found that the accumulation of PEP complexes is defective in both var6-1 and the null allele var6-2. Further protein interaction assays confirmed that VAR6/PAC interacts directly with the PAP2/pTAC2 and PAP3/pTAC10 subunits of PEP complexes. Moreover, we generated viable hypomorphic alleles of the essential gene PAP2/pTAC2, and revealed a genetic interaction between PAC and PAP2/pTAC2 in photosynthesis gene expression and PEP complex accumulation. Our findings establish that VAR6/PAC affects PEP complex accumulation through interactions with PAP2/pTAC2 and PAP3/pTAC10, and provide new insights into the accumulation of PEP and chloroplast development.

叶绿体基因组编码的光合作用基因转录主要由质体基因组编码的RNA聚合酶（PEP）介导。PEP类似于原核类型的RNA聚合酶，但具有一些植物特异性辅助亚基，称为质体转录活性染色体蛋白（pTACs）或PEP相关蛋白（PAPs）。然而，是否有其他蛋白因子参与PEP复合物的生物发生仍然未知。这里，我们研究了一个必需基因PALE CRESS（PAC）参与叶绿体PEP复合物积累。我们发现一个拟南芥“花斑”叶色突变体var6-1，是PAC的亚效等位突变体。出乎意料的是，我们发现PAC能够定位于类囊体膜，并与PEP复合物相互作用。此外，我们发现在var6-1和var6-2中PEP复合物的积累存在缺陷。进一步的蛋白相互作用证实PAC与PEP复合物的PAP2/pTAC2和PAP3/pTAC10亚基直接相互作用。此外，我们创制必需基因PAP2/pTAC2的亚效等位基因，并揭示了PAC和PAP2/pTAC2在光合作用基因表达和PEP复合物积累中的遗传相互作用。这些研究结果表明PAC通过与PAP2/pTAC2和PAP3/pTAC10的相互作用影响PEP复合物积累，为叶绿体发育提供了新的见解。

论文链接：http://doi.org/10.1111/nph.19243