Cysteine-rich repeats identified as markers of horizontal gene transfer in eukaryotes
Researchers identified a protein pattern called cysteine-rich repeats (CysRReps) that marks genes transferred horizontally between distantly related organisms in eukaryotes. The study found 859 eukaryotic proteins across 43 families sharing this pattern with bacterial, archaeal, and viral counterparts, suggesting a universal molecular mechanism for cross-domain gene transfer. This discovery could improve detection of horizontal gene transfer events, a process increasingly recognized as important for eukaryotic evolution but poorly understood mechanistically.
A bioRxiv preprint describes the discovery of cysteine-rich repeats as molecular signatures of horizontal gene transfer (HGT) in eukaryotes. Researchers used sequence analysis to identify an HGT-derived protein in the fungus Neocallimastix californica, then systematically searched for similar patterns across eukaryotic genomes. They identified 859 proteins in 43 families that share CysReps with prokaryotic counterparts spanning 15 bacterial phyla, archaeal species, and diverse viruses—particularly Caudoviricetes, suggesting virus-mediated DNA integration as a transfer mechanism. While the functional role of CysReps remains unknown, their consistent association with HGT events across phylogenetically distant organisms implies a conserved molecular mechanism facilitating gene transfer across domain boundaries. The findings address a significant gap in HGT research: the lack of targeted detection methods for identifying transferred genes in eukaryotes.
What's missing
The study does not discuss the evolutionary timescale of these HGT events (ancient vs. recent transfers), the functional consequences of CysRep-containing proteins for host organisms, or validation of the computational predictions through experimental methods. The authors acknowledge that CysRep function remains unclear, which limits interpretation of why this motif facilitates transfer.
What different sources said
- bioRxivCenter
Cysteine-rich repeats trace past horizontal gene transfers in eukaryotes
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