Evolution. Systematic humanization of yeast genes reveals conserved functions and genetic modularity.
Level 5 - mechanism / opinion, no new human data
Bench research / functional genomics screen in model organism (non-clinical)
PubMed 25999509 · doi:10.1126/science.aaa0769
What was done
Researchers systematically replaced 414 essential yeast (Saccharomyces cerevisiae) genes with their corresponding human orthologs. They then assayed whether the human genes could functionally complement lethal growth defects caused by loss of the endogenous yeast genes. Computational simulations were also performed to model functional retention and sequence divergence.
What was found
Of the 414 essential yeast genes tested, 47% were successfully humanized (complemented by their human ortholog). Sequence similarity and gene expression levels only partly predicted replaceability. Instead, functional replaceability grouped strongly by biological process modules: genes in specific pathways (e.g., sterol biosynthesis) tended to be replaceable, while genes in others (e.g., DNA replication initiation) were not.
Why it matters
This demonstrates that ancestral protein functions can remain conserved across a billion years of evolutionary divergence in a pathway-specific manner, resilient to sequence and interface drift.
Limits
The assay is restricted to essential genes in a unicellular organism under specific growth conditions, which cannot capture tissue-specific or complex developmental functions found in humans. Only 414 genes were assayed.
Cited by
- partial Approximately 70% of genes found in yeast share functional homologs in humans.