The RNA binding protein EHD6 recruits the m6A reader YTH07 and sequesters OsCOL4 mRNA into phase-separated ribonucleoprotein condensates to promote rice flowering
Song Cui, Peizhe Song, Chaolong Wang, Saihua Chen, Benyuan Hao, Zhuang Xu, Liang Cai, Xu Chen, Shanshan Zhu, Xiangchao Gan, Hui Dong, Yuan Hu, Liang Zhou, Haigang Hou, Yunlu Tian, Xi Liu, Liangming Chen, Shijia Liu, Ling Jiang, Haiyang Wang, Guifang Jia, Shirong Zhou, Jianmin Wan
Abstract
N 6 -Methyladenosine (m 6 A) is one of the most abundant modifications of eukaryotic mRNA, but its comprehensive biological functionality remains further exploration. In this study, we identified and characterized a new flowering-promoting gene, EARLY HEADING DATE6 ( EHD6 ), in rice. EHD6 encodes an RNA recognition motif (RRM)-containing RNA binding protein that is localized in the non-membranous cytoplasm ribonucleoprotein (RNP) granules and can bind both m 6 A-modified RNA and unmodified RNA indiscriminately. We found that EHD6 can physically interact with YTH07, a YTH (YT521-B homology) domain-containing m 6 A reader. We showed that their interaction enhances the binding of an m 6 A-modified RNA and triggers relocation of a portion of YTH07 from the cytoplasm into RNP granules through phase-separated condensation. Within these condensates, the mRNA of a rice flowering repressor, CONSTANS-like 4 ( OsCOL4 ), becomes sequestered, leading to a reduction in its protein abundance and thus accelerated flowering through the Early heading date 1 pathway. Taken together, these results not only shed new light on the molecular mechanism of efficient m 6 A recognition by the collaboration between an RNA binding protein and YTH family m 6 A reader, but also uncover the potential for m 6 A-mediated translation regulation through phase-separated ribonucleoprotein condensation in rice.