Biomolecular condensates - a regulatory hub for plant iron supply

Iron is a micronutrient. Plants require specific transcription factors (such as FIT and bHLH39) and light for iron sequestration. When plants are exposed to blue light under iron deficiency, transcription factors accumulate in the cell nucleus into biomolecular condensates, which may serve as molecular regulatory centers for excess iron acquisition. (Photo: HHU/Ksenia Trofimov, Petra Bauer) Credit: Journal of Cell Biology (2024). DOI: 10.1083/jcb.202311048

Iron is a micronutrient for plants. Biologists from the Institute of Botany at the Heinrich Heine University Düsseldorf (HHU) described in a study, now published I Journal of Cell Biology, that regulatory proteins for iron uptake in the cell nucleus behave particularly dynamically when cells are exposed to blue light – an important signal for plant growth. They found that the initially evenly distributed proteins moved together into “biomolecular condensates” in the cell nucleus shortly after this exposure.

Iron deficiency and excess are both problematic for plants. They require micronutrients for photosynthesis and enzymatic reactions. Iron deficiency causes yellowing of plants and reduced growth, while excess can cause cell damage. Therefore, iron should be used in balanced amounts to ensure healthy plant life.

Once the plant is a , a signaling cascade is activated and more iron is taken up by roots. Proteins that regulate specific genes (so-called transcription factors) play an important role in this process.

A research team from HHU’s Institute of Botany led by Prof. Dr. Petra Bauer examined the cellular localization of transcription factors involved in iron uptake, focusing in particular on an essential transcription factor within the iron signaling cascade called “FIT”. Focused.

To date, little research has been done on where in the nucleus transcription factors are located in the plant cell. However, knowing this will help in understanding the function of the protein. Whether the localization may change is also relevant, as it may be part of a regulatory mechanism that acts on the protein.

The study shows that FIT is a dynamic protein that can localize to membrane-less subcompartments—so-called biomolecular condensates—within the cell. The authors consider these subcompartments to be regulatory hubs that enable a spatially and temporally flexible platform for signaling and interaction.

Biologists found that FIT specifically accumulates in condensates. When plant cells are exposed to . They specifically examined blue light because it is an important environmental signal for plants and iron uptake.

The formation of some light-regulated protein condensates has already been described. Biomolecular condensates are formed when protein complexes locally aggregate. However, the association with dietary physiology-relevant components such as FIT has not previously existed. It was unclear whether FIT condensates could contribute to the organization and efficiency of cellular processes.

To this end, researchers in Düsseldorf examined the interactions between FIT and other proteins in nuclear condensates in more detail. They found that not only transcription but also the regulation of mRNA – that is, the parts of the genetic material that are read from DNA to control action – can occur in condensates.

“For the first time, I observed the accumulation of FIT proteins in the form of condensates during laboratory work on a master’s module project, which raised a simple question of why this is so,” lead author Dr. Ksenia Trofimov ( Now Krooß) says. This was the beginning of a major research project.

“When we saw these condensates forming, we had little idea what their function might be because the research topic of condensates was just emerging in the field of plants. The original question first led to my master’s work, and Then to my doctoral thesis.”

Professor Bauer added, “This work opens up a new aspect in plant nutrition. We now need to know more about how these condensates integrate into signaling cascades for iron uptake and how environmental cues such as Light is able to control the amount of iron. Fast and dynamic method.”

More information:
Ksenia Trofimov et al, FER-like iron deficiency-induced transcription factor (FIT) accumulates in nuclear condensates, Journal of Cell Biology (2024). DOI: 10.1083/jcb.202311048

Reference: Biomolecular condensates: regulatory hubs for plant iron supply (2024, February 23) Retrieved February 23, 2024, from https://phys.org/news/2024-02-biomolecular-condensates-regulatory-hubs-iron.html has been

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