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Convergent evolution links molybdenum insertase domains with organism-specific sequences

Summary

Scientists studied how fungi use a special protein called Mo insertase to create molybdenum cofactor, which is essential for life. By testing different versions of this protein from various organisms, they discovered that fungi have developed a unique version with a special 20-amino acid region that cannot be replaced with versions from plants or animals. This finding shows that evolution has fine-tuned this protein differently in different organisms.

Background

Molybdenum cofactor (Moco) biosynthesis is a highly conserved process essential for most eukaryotic organisms. The final steps of Moco biosynthesis are catalyzed by Mo insertase, which exists as either separate proteins in bacteria or as fused domains in higher organisms. The evolutionary significance of Mo insertase fusion and the role of linkage regions connecting these domains remain unclear.

Objective

To investigate why Mo insertase genes were repeatedly fused during eukaryotic evolution and to determine whether species-specific linkage sequences are functionally critical. The study aimed to understand the evolutionary importance of gene fusion in Mo insertase and its impact on Moco biosynthesis.

Results

Substituting the fungal linkage region with sequences from plants or mammals resulted in Moco deficiency and impaired nitrate-dependent growth. A critical 20-amino acid sequence (A184-G203) was identified as essential for fungal Mo insertase function. Structural modeling revealed this region forms a structured helix at the G domain trimer interface.

Conclusion

The study demonstrates that convergently evolved Mo insertase linkage regions are species-specific and cannot be interchanged. The A184-G203 region is crucial for proper Moco biosynthesis, likely functioning in substrate channeling or protein-protein interactions rather than catalytic activity itself.
  • Published in:Communications Biology,
  • Study Type:Molecular Biology Research,
  • Source: PMID: 39424966, DOI: 10.1038/s42003-024-07073-w
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