Multiscale structural evolution of proline-rich protein genes shapes primate salivary defenses.

Recurrent gene duplications, inversions, and tandem repeats drive the dynamic evolution of salivary proline-rich protein genes in primates, with humans showing reduced expression levels.

• Why it matters: Understanding how dietary ecology influences salivary protein gene evolution can reveal mechanisms of oral defense adaptation in mammals. The evolutionary processes shaping these genes remain unclear, especially across diverse primate lineages.
• What they did: Researchers analyzed 27 primate species using long-read genome assemblies, comparative genomics, phylogenetics, transcriptomics, and dietary data to investigate structural variation and expression patterns of PRP genes.
• The result: PRP genes are highly expressed in non-human primates' parotid glands despite structural variation, with humans exhibiting lower expression levels; lineage-specific repeats and adaptations, such as histidine-rich peptides in colobines, suggest mechanisms for modulating saliva composition and dietary defense.