HMYB1 interacts with HDA6 and is involved in flowering in Arabidopsis

組蛋白脫乙醯酶能將組蛋白離胺酸上乙醯基水解，進而調控染色體的結構和功能，影響基因的轉錄。根據我們實驗室酵母菌雙雜合系統以及液相層析串聯質譜儀的數據知道許多蛋白質可能與組蛋白脫乙醯酶HAD6有交互作用。本研究首先使用雙分子螢光互補去確認這些候選蛋白與HAD6之間是有交互作用，接下來挑選其中兩個MYB轉錄因子HMYB1(AT1G25550)和TRFL5 (AT1G15720)，進一步去研究其功能與特性。我們的結果得知這兩個蛋白是藉由DNA結合區域(MYB domain)與HAD6交互作用，此外HMYB1藉由雙色冷光系統測得為轉錄抑制子。HMYB1基因在根部、葉子以及幼苗時期有高表現,而TRFL5則是在種子有高表現。HMYB1基因過表達植株顯示有晚開花現象。在HMYB1基因過表達植株，影響開花的抑制子FLC以及整合蛋白FT的基因表現都受到了影響。此外通過人工小分子RNA（artificial microRNA）降低HMYB1基因表現可以造成阿拉伯芥提早開花的情形。以上結果表明阿拉伯芥HMYB1與HDA6交互作用並且參與開花調控。Histone deacetylases mediate histone deacetylation and act in concert with histone acetyltransferases to regulate dynamic and reversible histone acetylation, which modifies chromatin structure and affects gene transcription. By using yeast two hybrid library screening and LC-mass/mass analysis, many proteins that interact with HISTONE DEACETYLASE 6 (HDA6) were identified. The interaction of HDA6 with these identified proteins was further confirmed by bimolecular fluorescence complementation assays. HMYB1 (At1G25550) and TRFL5 (At1G15720), two MYB transcription factors interacting with HDA6, were selected to further study their function. Our results show that their MYB domains are required for the interaction with HDA6 and HMYB1 is transcriptional repressor by dual-luciferase reporter assay. HMYB1 is highly expressed in roots and rosette leaves, but TRFL5 is highly expressed in seeds Furthermore, HMYB1 overexpression plants (HMYB1-OE) show delayed flowering, and FLC is upregulated but FT is downregulated in HMYB1-OE plants. We also generated HMYB1 knockdown transgenic plants (Ami-HMYB1) by using artificial microRNA. Ami-HMYB1 plants exhibit early flowering. Taken together, our results indicate that HMYB1 is a transcriptional repressor interacting with HDA6 and is involved in flowering in Arabidopsis