EME1s

EME1s refers to the family of essential meiotic endonuclease 1 homolog proteins, which serve as partners in the MUS81-EME1 structure-specific nuclease complex. Across eukaryotes, EME1 family members form heterodimers with MUS81 and are conserved components of a nuclease machinery that processes DNA secondary structures. The MUS81-EME1 complex is especially important for resolving unusual DNA substrates that arise during replication and recombination, such as stalled forks, 5' and 3' flaps, and Holliday junction–like structures.

Functionally, EME1s contribute to genome stability by enabling controlled processing of DNA structures that, if left unresolved, can lead to chromosome missegregation or mutations. In cells, the MUS81-EME1 complex acts in coordination with other repair pathways and is engaged during S and G2 phases of the cell cycle, particularly under conditions of replication stress or DNA damage. EME1s also have realized roles in meiosis in some organisms, where they assist in the maturation of crossover precursors and maintenance of chromosomal integrity.

Regulation of EME1s involves cellular context and post-translational modifications that influence complex formation, localization, and nuclease activity. Interactions with the catalytic MUS81 subunit and with scaffold proteins such as SLX4 help organize nuclease activity at sites of damage. In humans, alternatives to EME1 exist (for example, EME2 can partner with MUS81) that expand the range of substrates processed by this nuclease family.

Clinical relevance is linked to genome stability; defects or altered regulation of MUS81-EME1–type nucleases can contribute to sensitivity to DNA-damaging agents and genomic instability, with implications for cancer biology and potential therapeutic targeting.