Research Focus: Ribonucleotide Reductases (RNRs)

TL;DR

Ribonucleotide reductase is a crucial enzyme for DNA biosynthesis and repair, targeted by therapeutic drugs for cancer treatment. Its unique chemistry involves radicals and metal cofactors, playing a role in the transition from an RNA world to a DNA world.

Transcript

JOANNE STUBBE: My lab works on the only cool enzyme in the world-- ribonucleotide reductase. It's the only way in all organisms that you make the building blocks de novo that are required for DNA biosynthesis and repair. So if you inhibit this enzyme, you have no building blocks. You can't survive. So from a practical point of view, it's the target... Read More

Key Insights

• 🤩 Ribonucleotide reductase is the key enzyme responsible for DNA biosynthesis in all organisms.
• ♋ Inhibiting ribonucleotide reductase is a potential therapeutic strategy for cancer and future antibacterials.
• 👻 Radicals are essential for ribonucleotide reductase's chemistry, allowing for precise reactions.
• 😲 The tyrosyl radical, involved in ribonucleotide reductase's chemistry, has astonishing stability in the enzyme's active site.
• 🖐️ Metal cofactors play a crucial role in facilitating the oxidation of tyrosine to the tyrosyl radical.
• 🤘 Ribonucleotide reductases have evolved with different metal cofactors but maintain the same active site and chemistry.
• ❓ The uniqueness of ribonucleotide reductase's chemistry challenges introductory course curriculums, which rarely discuss radical-mediated transformations.

Questions & Answers

Q: Why is ribonucleotide reductase a vital target for cancer treatment?

Ribonucleotide reductase produces the building blocks required for DNA synthesis. By inhibiting this enzyme, cancer cells are stripped of their ability to replicate DNA, hindering their growth and compromising their survival.

Q: How does ribonucleotide reductase use radicals for its chemistry?

Ribonucleotide reductase relies on the formation of a tyrosyl radical, which is oxidized from tyrosine. This radical participates in various reactions, enabling the enzyme to carry out complex chemistry with precision and specificity.

Q: What is the role of metal cofactors in ribonucleotide reductase?

Metal cofactors, such as cobalt, iron sulfur clusters, manganese, and iron, facilitate the oxidation of tyrosine to the tyrosyl radical. They play a crucial role in generating the radical necessary for the enzyme's function.

Q: How does ribonucleotide reductase contribute to the transition from an RNA world to a DNA world?

Ribonucleotide reductases are involved in the production of building blocks for DNA synthesis, a crucial step in the transition from RNA to DNA. Different classes of ribonucleotide reductases utilize the same chemistry but with different metal cofactors, potentially indicating their evolutionary origin.

Summary & Key Takeaways

• Ribonucleotide reductase is the only enzyme that produces the necessary building blocks for DNA synthesis and repair.

• Inhibiting this enzyme is a target for cancer drugs and potentially antibacterials.

• The enzyme's chemistry involves radicals, specifically the oxidation of tyrosine, and the function of metal cofactors.