6mC

6-Methylcytosine (6mC) is a chemical modification of the DNA base cytosine, characterized by the addition of a methyl group at the 6th carbon position. It is considered an epigenetic mark that influences gene expression without altering the underlying DNA sequence. While 5-methylcytosine (5mC) is well known for its role in mammals and many eukaryotes, 6mC has been primarily identified in certain prokaryotes, algae, and some lower eukaryotes, although recent research suggests it may also occur in mammalian genomes under specific conditions.

In bacteria, 6mC functions as part of the restriction-modification system, protecting the host genome from restriction enzymes by methylating specific DNA sequences. It also participates in DNA replication, repair, and regulation of gene expression. The presence of 6mC in eukaryotic DNA has been less studied, but emerging evidence indicates that it may play roles in regulating gene activity, chromatin structure, and genome stability, particularly during development or in response to environmental factors.

Detection methods for 6mC include advanced sequencing technologies and mass spectrometry. Its occurrence, distribution, and functional significance are still areas of active investigation. Understanding 6mC's role could provide insights into mechanisms of epigenetic regulation and potential implications for developmental biology, disease states, and biotechnology.

Unlike 5mC, which has been extensively studied, 6mC remains relatively less characterized, with ongoing research aimed at elucidating its biological functions and how it interacts with other epigenetic modifications. Overall, 6mC is an important but less understood DNA methylation mark with potential significance across diverse species and biological processes.