Shape shifting RNA

---

Shape shifting RNA

For lots of plants it is important to know when it is winter, and when winter is gone. They adjust their growth accordingly. Plants, for example, often flower only after they have gone through a period of cold. We know lost about how plants are regulating this. But how plants perceive cold remains a question to be answered.

Now researchers from England showed how one of the regulators of flowering is changing shape when the temperature changes. The regulator in question is the RNA molecule COOLAIR. COOLAIR influences how much of the flower-repressor is present. Is it warm, then COOLAIR allows lots of the flower-repressor. But is it cold, then COOLAIR is turning off the flower-repressor, allowing the plant to flower. But how COOLAIR is doing this was up to now unknown.

Just like proteins RNA-molecules fold into shape. The shape of proteins is largely temperature independent. In contrast the shape of RNA molecules changes depending on the temperature. To analyse into which shape COOLAIR fold itself when it is warm or cold the researchers developed a method to determine the shape of each individual RNA molecule. This showed the researchers that COOLAIR has four favourite folds.

---

By having a specific cold fold, COOLAIR is influencing the flower-repressor only when it is cold

---

Two of those occur both during warm and cold temperatures, although in a different ratio. Of the other two folds, one is observed during warm temperatures, while the other is there only when it is cold. The researchers noticed that the cold specific fold was distinctly differently folded in one place compared to the other observed COOLAIR folds. This gave the researchers a hind how COOLAIR could turn off the flower-repressor.

Using mutations the researchers changed the shape of the cold specific COOLAIR fold, to test if unique cold specific COOLAIR fold was responsible for turning off the flower-repressor. Subsequently the researchers studied the COOLAIR mutant plants. The plants with the COOLAIR mutation turned off more of the flower-repressor than the non-mutated plants. Moreover, they were also flowering quicker after a period of cold. The cold COOLAIR-variant is responsible for switching off the flower-repressor.

By having a specific cold fold, COOLAIR is influencing the flower-repressor only when it is cold. And a change in this cold-COOLAIR fold is influencing when a plant is flowering. As this is showing, RNA molecules help plants to perceive temperature changes. Through shape shifting by changing temperatures. In this way RNA molecules can change function in response to a changing environment without receptor intermediates. Enabling COOLAIR to respond to cooler air.

Literature

Yang, M., Zhu, P., Cheema, J., Bloomer, R., Mikulski, P., Liu, Q., Zhang, Y., Dean, C., Ding, Y. (2022) In vivo single-molecule analysis reveals COOLAIR RNA structural diversity. Nature https://doi.org/10.1038/s41586-022-05135-9