Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina.
J Plant Physiol. 2010 Feb 15;167(3):194-200. doi: 10.1016/j.jplph.2009.09.003. Epub 2009 Sep 26.
Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) type belong to a small multigenic family that controls gene expression by connecting transcription factors and the basal transcription machinery. In this report, a triple knock-down mutant (abc-) for the Arabidopsis thaliana MBF1 genes AtMBF1a, AtMBF1b and AtMBF1c was generated. The phenotypic characterization using oxidative agents such as hydrogen peroxide and methyl viologen revealed that the abc- mutant was more sensitive to oxidative stress. The triple knock-down mutant, abc- was also sensitive to osmotic stress mediated by high concentrations of sorbitol. Furthermore, the abc- phenotype was partially or completely rescued by AtMBF1c cDNA over-expression (abc- +c) depending on physiological and developmental conditions. AtMBF1s regulate the expression of ABR1, which is a member of the ethylene-response factor family and acts as ABA repressor. Thus, we conclude that AtMBF1 gene family may function as a regulatory component of the cross-talk node between ethylene, ABA and stress signal pathways. Furthermore, higher levels of a HSP70 mRNA and an immunoreactive HSP70 protein were detected in the abc- mutant. The participation of MBF1c as a possible negative regulator of HSP genes was discussed.
转录辅激活因子的多蛋白桥接因子 1（MBF1）型属于一个小的多基因家族，通过连接转录因子和基础转录机制来控制基因表达。在本报告中，生成了拟南芥 MBF1 基因 AtMBF1a、AtMBF1b 和 AtMBF1c 的三重敲除突变体（abc-）。使用过氧化氢和甲基紫精等氧化剂进行表型特征分析表明，abc-突变体对氧化应激更为敏感。三重敲除突变体 abc-也对高浓度山梨醇介导的渗透胁迫敏感。此外，abc-表型部分或完全通过 AtMBF1c cDNA 过表达（abc-+c）得到挽救，具体取决于生理和发育条件。AtMBF1 调节 ABR1 的表达，ABR1 是乙烯反应因子家族的成员，作为 ABA 抑制剂发挥作用。因此，我们得出结论，AtMBF1 基因家族可能作为乙烯、ABA 和应激信号途径之间串扰节点的调节成分发挥作用。此外，在 abc-突变体中检测到 HSP70 mRNA 和免疫反应性 HSP70 蛋白的水平升高。讨论了 MBF1c 作为 HSP 基因的可能负调节剂的参与。
