State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.
Shenzhen Research Institute of Nanjing University, Shenzhen, China.
Plant Signal Behav. 2021 Nov 2;16(11):1964847. doi: 10.1080/15592324.2021.1964847. Epub 2021 Aug 18.
ORANGE (OR) is a member of the DnaJ-like zinc finger domain-containing protein family, of which all orthologs share a highly conserved quadruple repeat of the CxxCxxxG signatures at their C-termini. Dual subcellular localization and different interacting partner proteins have been reported for OR. In plastids, OR interacts with phytoene synthase, the entry enzyme for carotenoid biosynthesis, to promote chromoplast biogenesis and carotenoid accumulation in non-pigmented tissues. In the nucleus, OR interacts with the eukaryotic release factor eRF1-2 to regulate cell elongation in the petiole, and with the transcription factor TCP14 to repress the expression of () and chloroplast biogenesis in de-etiolating cotyledons. In this study, we demonstrated the E2 ubiquitin-conjugating enzyme UBC19 as a new interacting partner of OR. The lysine of OR was found to be ubiquitinated, and OR lost its nuclear localization and the capability in repressing when lysine was substituted by alanine. Our findings raised the possibility that the ubiquitination by UBC19 is essential for the nuclear localization of OR.
橙色蛋白（OR）是 DnaJ 样锌指蛋白家族的成员，其所有直系同源物在 C 末端都具有高度保守的四重复 CxxCxxxG 特征。已经报道了 OR 的双重亚细胞定位和不同的相互作用蛋白。在质体中，OR 与类胡萝卜素生物合成的入口酶——phytoene synthase 相互作用，以促进质体生物发生和非色素组织中的类胡萝卜素积累。在细胞核中，OR 与真核释放因子 eRF1-2 相互作用以调节叶柄的细胞伸长，并与转录因子 TCP14 相互作用以抑制脱黄化子叶中 () 和叶绿体生物发生的表达。在这项研究中，我们证明了泛素结合酶 E2 UBC19 是 OR 的一个新的相互作用伙伴。发现 OR 的赖氨酸被泛素化，并且当赖氨酸被丙氨酸取代时，OR 失去了其核定位和抑制的能力。我们的发现提出了泛素化由 UBC19 进行对于 OR 的核定位是必不可少的可能性。
