Evolutionary pathways of an ancient gene recX

Area of Science:

• Molecular Biology
• Genomics
• Evolutionary Biology

Background:

• RecX protein regulates RecA activity by interacting with RecA proteins or filaments.
• RecX genes are present in diverse bacteria and some plants, but absent in archaea.

Purpose of the Study:

• To investigate the evolutionary origin and dissemination of RecX genes.
• To explore the relationship between bacterial and plant RecX domains and the formation of plant RecX-like proteins.

Main Methods:

• Comparative genome analysis of RecX family genes across various species.
• Phylogenetic analysis to infer evolutionary relationships.
• Examination of gene fusion events in plant RecX-like protein formation.

Main Results:

• RecX genes are widespread in bacteria but absent in archaea.
• The sole eukaryotic RecX gene is likely of bacterial origin, suggesting RecX originated in the bacterial common ancestor.
• Bacterial and plant RecX domains are homologous, with plant RecX domains potentially acquired from bacteria.
• Plant RecX-like proteins result from gene fusion involving a RecX domain and an N-terminal domain of unknown origin.

Conclusions:

• RecX is of bacterial origin and was present in the bacterial common ancestor.
• Horizontal gene transfer from bacteria to plants likely facilitated the presence of RecX in plants.
• Plant RecX-like proteins evolved through gene fusion events, integrating bacterial RecX domains.