Chromatin structure is critical for gene expression and many other cellular processes. In Arabidopsis thaliana, the floral repressor FLC adopts a self-loop chromatin structure via bridging of its flanking regions. This local gene loop is necessary for active FLC expression. However, the molecular mechanism underlying the formation of this class of gene loops is unknown. Here, we report the characterization of a group of linker histone-like proteins, named the GH1-HMGA family in Arabidopsis, which act as chromatin architecture modulators. We demonstrate that these family members redundantly promote the floral transition through the repression of FLC. A genome-wide study revealed that this family preferentially binds to the 5′ and 3′ ends of gene bodies. The loss of this binding increases FLC expression by stabilizing the FLC 5′ to 3′ gene looping. Our study provides mechanistic insights into how a family of evolutionarily conserved proteins regulates the formation of local gene loops.

染色质结构对于基因表达和许多其他细胞过程至关重要。在拟南芥中，花抑制因子FLC通过桥接其侧翼区域采用自环染色质结构。该局部基因环对于活跃的FLC表达是必需的。然而，此类基因环形成的分子机制尚不清楚。在这里，我们报告了拟南芥中一组连接组蛋白样蛋白的特征，这些蛋白被称为 GH1-HMGA 家族，它们充当染色质结构调节剂。我们证明这些家庭成员通过抑制FLC过度促进了花的转变。一项全基因组研究表明，该家族优先结合基因体的 5' 和 3' 端。这种结合的丧失通过稳定FLC 5' 至 3' 基因环来增加FLC表达。我们的研究提供了关于进化上保守的蛋白质家族如何调节局部基因环的形成的机制见解。