Carranco Raúl, Prieto-Dapena Pilar, Almoguera Concepción, Jordano Juan
Departamento de Biotecnología Vegetal, Instituto de Recursos Naturales y Agrobiología de Sevilla, Consejo Superior de Investigaciones CientíficasSeville, Spain.
Front Plant Sci. 2017 Jun 13;8:974. doi: 10.3389/fpls.2017.00974. eCollection 2017.
A transcriptional synergism between HaHSFA9 (A9) and HaHSFA4a (A4a) contributes to determining longevity and desiccation tolerance of sunflower (, L.) seeds. Potential lysine SUMOylation sites were identified in A9 and A4a and mutated to arginine. We show that A9 is SUMOylated at K38. Although we did not directly detect SUMOylated A4a , we provide indirect evidence from transient expression experiments indicating that A4a is SUMOylated at K172. Different combinations of wild type and SUMOylation site mutants of A9 and A4a were analyzed by transient expression in sunflower embryos and leaves. Although most of the precedents in literature link SUMOylation with repression, the A9 and A4a synergism was fully abolished when the mutant forms for both factors were combined. However, the combination of mutant forms of A9 and A4a did not affect the nuclear retention of A4a by A9; therefore, the analyzed mutations would affect the synergism after the mutual interaction and nuclear co-localization of A9 and A4a. Our results suggest a role for HSF SUMOylation during late, zygotic, embryogenesis. The SUMOylation of A9 (or A4a) would allow a crucial, synergic, transcriptional effect that occurs in maturing sunflower seeds.
HaHSFA9（A9）和HaHSFA4a（A4a）之间的转录协同作用有助于决定向日葵（Helianthus annuus L.）种子的寿命和耐旱性。在A9和A4a中鉴定出潜在的赖氨酸SUMO化位点，并将其突变为精氨酸。我们发现A9在K38位点发生SUMO化。尽管我们没有直接检测到SUMO化的A4a，但我们从瞬时表达实验中提供了间接证据，表明A4a在K172位点发生SUMO化。通过在向日葵胚和叶片中的瞬时表达，分析了A9和A4a野生型和SUMO化位点突变体的不同组合。尽管文献中的大多数先例将SUMO化与抑制作用联系起来，但当两种因子的突变形式组合时，A9和A4a的协同作用完全消失。然而，A9和A4a突变形式的组合并不影响A9对A4a的核滞留作用；因此，所分析的突变将在A9和A4a相互作用和核共定位后影响协同作用。我们的结果表明HSF SUMO化在合子后期胚胎发生过程中发挥作用。A9（或A4a）的SUMO化将允许在成熟向日葵种子中发生关键的、协同的转录效应。
