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Molecular Biology Commons

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2016

Enzyme mechanisms

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Full-Text Articles in Molecular Biology

Deciphering The Tetrad Of Epigenetic Cytosine Modifications, Monica Yun Liu Jan 2016

Deciphering The Tetrad Of Epigenetic Cytosine Modifications, Monica Yun Liu

Publicly Accessible Penn Dissertations

A tetrad of epigenetic cytosine modifications imbues the DNA code with complex, dynamic meaning. DNA methyltransferase enzymes deposit methyl marks on the 5-carbon of cytosine, forming 5-methylcytosine (mC), which generally mediates long-term, locus-specific transcriptional repression during development and reprogramming. Ten-eleven translocation (TET) family enzymes oxidize the methyl group in three steps, forming predominantly 5-hydroxymethylcytosine (hmC) but also low levels of 5-formylcytosine (fC) and 5-carboxylcytosine (caC). These additional bases likely provide pathways for erasing methylation, but they may also harbor epigenetic functions in their own right. Questions regarding how each base forms and functions drive at the fundamental biology of the ...