The Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China.
J Integr Plant Biol. 2013 Nov;55(11):1002-15. doi: 10.1111/jipb.12089. Epub 2013 Oct 23.
Formins are well-known regulators that participate in the organization of the actin cytoskeleton in organisms. The Arabidopsis thaliana L. genome encodes 21 formins, which can be divided into two distinct subfamilies. However, type II formins have to date been less well characterized. Here, we cloned a type II formin, AtFH16, and characterized its biochemical activities on actin and microtubule dynamics. The results show that the FH1FH2 structure of AtFH16 cannot nucleate actin polymerization efficiently, but can bind and bundle microfilaments. AtFH16 FH1FH2 is also able to bind and bundle microtubules, and preferentially binds microtubules over microfilaments in vitro. In addition, AtFH16 FH1FH2 co-localizes with microtubules in onion epidermal cells, indicating a higher binding affinity of AtFH16 FH1FH2 for microtubules rather than microfilaments in vivo. In conclusion, AtFH16 is able to interact with both microfilaments and microtubules, suggesting that AtFH16 probably functions as a bifunctional protein, and may thus participate in plant cellular processes.
成核因子是参与生物体内肌动蛋白细胞骨架组织的众所周知的调节剂。拟南芥基因组编码 21 种成核因子，可分为两个不同的亚家族。然而，迄今为止，对 II 型成核因子的研究还较少。本研究克隆了一个 II 型成核因子 AtFH16，并对其在肌动蛋白和微管动力学上的生化活性进行了表征。结果表明，AtFH16 的 FH1FH2 结构不能有效地起始肌动蛋白聚合，但可以结合并束集微丝。AtFH16 FH1FH2 还能够结合并束集微管，并且在体外优先结合微管而不是微丝。此外，AtFH16 FH1FH2 在洋葱表皮细胞中与微管共定位，表明 AtFH16 FH1FH2 在体内与微管的结合亲和力高于微丝。综上所述，AtFH16 能够与微丝和微管相互作用，这表明 AtFH16 可能作为一种双功能蛋白发挥作用，从而可能参与植物细胞过程。
