Koch Aline, Kang Hong-Gu, Steinbrenner Jens, Dempsey D'Maris A, Klessig Daniel F, Kogel Karl-Heinz
Centre for BioSystems, Land Use and Nutrition, Institute for Phytopathology, Justus Liebig University Giessen, Giessen, Germany.
Department of Biology, Texas State University, San Marcos, TX, United States.
Front Plant Sci. 2017 Oct 18;8:1720. doi: 10.3389/fpls.2017.01720. eCollection 2017.
Microrchidia (MORC) proteins comprise a family of proteins that have been identified in prokaryotes and eukaryotes. They are defined by two hallmark domains: a GHKL-type ATPase and an S5 fold. MORC proteins in plants were first discovered via a genetic screen for Arabidopsis mutants compromised for resistance to a viral pathogen. Subsequent studies expanded their role in plant immunity and revealed their involvement in gene silencing and transposable element repression. Emerging data suggest that MORC proteins also participate in pathogen-induced chromatin remodeling and epigenetic gene regulation. In addition, biochemical analyses recently demonstrated that plant MORCs have topoisomerase II (topo II)-like DNA modifying activities that may be important for their function. Interestingly, animal MORC proteins exhibit many parallels with their plant counterparts, as they have been implicated in disease development and gene silencing. In addition, human MORCs, like plant MORCs, bind salicylic acid and this inhibits some of their topo II-like activities. In this review, we will focus primarily on plant MORCs, although relevant comparisons with animal MORCs will be provided.
微小染色体相关蛋白（MORC）家族蛋白已在原核生物和真核生物中被鉴定出来。它们由两个标志性结构域定义：一个GHKL型ATP酶和一个S5折叠。植物中的MORC蛋白最初是通过对拟南芥突变体进行遗传筛选发现的，这些突变体对病毒病原体的抗性受损。随后的研究扩展了它们在植物免疫中的作用，并揭示了它们参与基因沉默和转座子抑制。新出现的数据表明，MORC蛋白也参与病原体诱导的染色质重塑和表观遗传基因调控。此外，最近的生化分析表明，植物MORC具有类似拓扑异构酶II（topo II）的DNA修饰活性，这可能对其功能很重要。有趣的是，动物MORC蛋白与其植物对应物表现出许多相似之处，因为它们与疾病发展和基因沉默有关。此外，人类MORC与植物MORC一样，能结合水杨酸，这会抑制它们一些类似topo II的活性。在这篇综述中，我们将主要关注植物MORC，不过也会提供与动物MORC的相关比较。
