Details

Autor(en) / Beteiligte

• Kosel, Brinja
• Bigler, Katrin
• Buchmuller, Benjamin C.
• Acharyya, Suchandra R.
• Linser, Rasmus
• Summerer, Daniel

Titel

Evolved Readers of 5‐Carboxylcytosine CpG Dyads Reveal a High Versatility of the Methyl‐CpG‐Binding Domain for Recognition of Noncanonical Epigenetic Marks

Ist Teil von

• Angewandte Chemie International Edition, 2024-04, Vol.63 (17), p.e202318837-n/a

Auflage

International ed. in English

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2024

Quelle

MEDLINE

Beschreibungen/Notizen

• Mammalian genomes are regulated by epigenetic cytosine (C) modifications in palindromic CpG dyads. Including canonical cytosine 5‐methylation (mC), a total of four different 5‐modifications can theoretically co‐exist in the two strands of a CpG, giving rise to a complex array of combinatorial marks with unique regulatory potentials. While tailored readers for individual marks could serve as versatile tools to study their functions, it has been unclear whether a natural protein scaffold would allow selective recognition of marks that vastly differ from canonical, symmetrically methylated CpGs. We conduct directed evolution experiments to generate readers of 5‐carboxylcytosine (caC) dyads based on the methyl‐CpG‐binding domain (MBD), the widely conserved natural reader of mC. Despite the stark steric and chemical differences to mC, we discover highly selective, low nanomolar binders of symmetric and asymmetric caC‐dyads. Together with mutational and modelling studies, our findings reveal a striking evolutionary flexibility of the MBD scaffold, allowing it to completely abandon its conserved mC recognition mode in favour of noncanonical dyad recognition, highlighting its potential for epigenetic reader design. Cytosine 5‐modifications–occurring in different combinations in the two DNA strands of CpG dyads–are central to human chromatin regulation, but the customized recognition of such combinatorial marks is challenging. By re‐evolving MBDs, the readers of canonical 5‐methylated CpGs, we identify strong and selective readers of noncanonical 5‐carboxylcytosine‐containing CpGs that have fully abandoned the conserved recognition of methylated CpGs.