Protein Subunit-Subunit to Domain-Domain Interactions

Abstract

Fusion proteins often referred to as “rosetta stone” occur through an important evolutionary phenomenon called gene fusion. This results in chimeric sequences in one species compared to its unfused individual component sequences in yet another species. Thus, a functional “subunit-subunit” interface in one species has evolved to form a functional “domain-domain” interface in yet another species. Therefore, it is important to describe such events and its possible mechanism with appropriate hypothesis using available structural complexes of some known examples. We describe this phenomenon using illustrations of chimeric protein sequences in comparison with known structures for both fused and unfused forms.

Exercises

• 1. What is a chimera protein?

• 2. What is a rosetta stone?

• 3. What is a fusion protein?

• 4. Show the HisF-HisH interface in T. thermophilus (TT) and S. cerevisiae (SC) using a neat diagram.

• 5. What is gene fusion?

• 6. Illustrate the structural evidence for fusion proteins using examples

• 7. Enumerate the mechanism of gene fusion.

• 8. Describe the hypothesis of gene fusion.

• 9. Illustrate the evolutionary pressure for gene fusion using examples.

• 10. What is gap index?

• 11. Give an account of fusion proteins using known structures.

• 12. Illustrate the DNA gyrase A and B interface with its fusion counterpart.

• 13. Illustrate the acetate CoA transferase α and β interface with its fusion counterpart.

• 14. Illustrate the DNA pol III α and ε interface with its fusion counterpart.

• 15. Illustrate the glutamyl phosphate reductase and glutamate kinase interface with its fusion counterpart.

• 16. Illustrate the His2-His10 interface with its fusion counterpart.