结果：Here, we show that the substrate specificity of the Arabidopsis histone demethylase JMJ16 is broadened from Lys 4 of histone H3 (H3K4) alone in somatic cells to both H3K4 and H3K9 when it binds to the meiocyte-specific histone reader MMD1. Consistent with this, the JMJ16 catalytic domain exhibits both H3K4 and H3K9 demethylation activities. Moreover, the JMJ16 C-terminal FYR domain interacts with the JMJ16 catalytic domain and probably restricts its substrate specificity. By contrast, MMD1 can compete with the N-terminal catalytic domain of JMJ16 for binding to the FYR-C domain, thereby expanding the substrate specificity of JMJ16 by preventing the FYR domain from binding to the catalytic domain.

结论：We propose that MMD1 and JMJ16 together in male meiocytes promote gene expression in an c-dependent manner and thereby contribute to meiotic chromosome condensation.

 摘  要 

组蛋白去甲基化对于正确的染色质结构以及保证正常的发育都至关重要，并且该过程需要含有JmjC功能域的组蛋白去甲基化酶的参与。但是，目前对于含有JmjC功能域的组蛋白去甲基化酶的底物特异性分子机制研究仍然存在较大空白。本文中，作者的研究显示拟南芥组蛋白去甲基化酶JMJ16在体细胞中特异性靶向H3K4底物，但是在结合了减数母细胞特异性组蛋白reader蛋白MMD1后其能够同时靶向H3K4和H3K9底物。与此一致的是，JMJ16催化域同时存在H3K4和H3K9的去甲基化活性。此外，JMJ16蛋白C端的FYR结构域能够与JMJ16的催化域互作，可能限制其催化域的底物特异性。相反，MMD1可以与JMJ16蛋白C端FYR结构域竞争结合JMJ16蛋白N端的催化域，从而通过防止C端的FYR结构域结合N端的催化域来拓展JMJ16蛋白的底物特异性。作者提出，MMD1与JMJ16一起在雄性减数分裂细胞中通过一种H3K9me3依赖性的方式促进基因的表达，从而作用于减数分裂时的染色体凝聚。

 通讯作者