@article {333878, title = {Evolution-guided yeast complementation reveals functional differences in human PSPH variants}, journal = {FEBS Open Bio}, year = {2026}, month = {2026/08/05}, abstract = {

Deciphering how human genetic variants affect conserved metabolic enzymes is essential for understanding their evolutionary and clinical significance. Here, we combine sequence analyses of temporally stratified human genomes with a quantitative\ Saccharomyces cerevisiae\ complementation assay in a strain lacking\ SER2, the yeast gene required for the final step of L-serine biosynthesis, to examine functional differences among human phosphoserine phosphatase (PSPH) variants. Population-genomic comparisons between ancient hunter-gatherers and present-day humans identified two\ PSPH\ exons with elevated differences in nucleotide diversity, guiding the selection of two ancient-genome-prioritized variants (R27S and Q83H) for functional testing. To place their effects in functional context, we expressed each variant individually and compared complementation with the modern\ PSPH\ allele and two disease-associated alleles (D32N and A35T) across multiple environmental conditions. Human\ PSPH\ enhanced growth of the\ SER2\ deletion mutant and revealed reproducible quantitative differences among alleles. The modern allele generally conferred the strongest complementation, while the ancient genome variants supported measurable but more condition-dependent rescue, and the disease-associated alleles showed the weakest complementation. These differences were broadly consistent across conditions, while specific environmental perturbations revealed context-dependent shifts in effect size. Together, our results establish a scalable framework that links evolutionary genomics with experimental functional assays to identify and evaluate human metabolic enzyme variants with measurable\ in vivo\ effects.

}, isbn = {2211-54632211-5463}, doi = {http://dx.doi.org/10.1002/2211-5463.70308}, url = {https://febs.onlinelibrary.wiley.com/doi/10.1002/2211-5463.70308}, author = {Campa-{\'A}lvarez, Mauricio and Ascencio, Diana and Vallebueno-Estrada, Miguel and Gonz{\'a}lez-Orozco, Eduardo and Mart{\'\i}nez-Guerrero, Christian Eduardo and Montiel, Rafael and DeLuna, Alexander} }