Can Fe2+ and Mn2+ protect the ribosome under oxidative stress conditions?

Husna, Amity University Kolkata

Protein biosynthesis is the basic need of cellular life for which it requires the systematic functioning of the translational machinery. At the centre of this machinery, the ribosome is present which is a ribonucleoprotein complex and depends heavily on Mg²⁺ for its structure.

 Recent experimental studies indicate that other metal cations can substitute for Mg²⁺ which raises the questions on the role that different metals may play for the maintenance of the ribosome under oxidative stress conditions. Ribosomal integrity was assessed following oxidative stress both in vitro and inside the cells to explain interactions between Fe²⁺ and the ribosome and identify Mn²⁺ as an element capable of reducing the degradation of rRNA by Fe²⁺– mediated oxidation. Fe²⁺ promotes degradation of all rRNA species of the yeast ribosome and it binds onto RNA molecules. Moreover, it was observed that Mn²⁺ competes with Fe²⁺ for rRNA binding sites, and it also protects ribosomes from Fe²⁺– mediated rRNA hydrolysis. The studies suggested a relationship between the transition metals Fe²⁺ and Mn²⁺ in controlling the ribosome stability under oxidative stress conditions.

Mn²⁺ doesn’t induce 25S rRNA fragmentation in the presence of ascorbic acid in the manner that Fe²⁺ does and when both metal ions are present Mn²⁺

 inhibits Fe²⁺ mediated rRNAs hydrolysis. This implies that Mn²⁺ occupies and competes for identical sites as Fe²⁺ on the ribosome and it can defend against oxidative damage by displacing Fe and by preventing hydrolytic cleavages throughout the ribosomal RNAs. So Mn is necessary and should be present along with an excess of Fe to provide a significant protective effect on rRNA integrity.

In conclusion, manganese can protect cells from oxidative stress while iron can enhance oxidant-induced damage and these two transition metal neighbours can substitute each other at the identical sites of biomolecules which provides stability to the translation.

Also read: COVID UPDATE: Decrease in daily active cases in India

SOURCE: Iron-mediated degradation of ribosomes under oxidative stress is attenuated by manganese.Daniel G.J. Smethurst, Nikolay Kovalev, Erica R. McKenzie, Dimitri G. Pestov, and Natalia Shcherbik https://www.jbc.org/content/early/2020/10/09/jbc.RA120.015025

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