Biochemists at the University of Münster have developed a new technique for regulating the biological functions of DNA using light, which provides a new method for investigating cell processes.

Using so-called protein engineering, the researchers engineered one enzyme in the cascade which can be switched on and off by means of light, making it possible to switch DNA functions on and off. With the assistance of protein design, it was possible to design proteins capable of adding methyl groups to adenosines (MATs). Study the authors performed on two MATs. The modifications they carried out can be extended to other MATs with a wider substrate scope.

The functions of the cell depend on the enzymes, special molecules. Enzymes are proteins that conduct cell-based chemical reactions. They lead to synthesizing metabolic products, copying DNA molecules, converting energy for cell function, epigenetically modifying DNA and breaking down those molecules. In order to understand and monitor such functions, a team of researchers led by professor Andrea Rentemeister at the University of Münster's Institute of Biochemistry used a so-called enzyme cascading reaction.

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This series of subsequent reaction steps with different enzymes allows so-called photo-groups – chemical groups that can be extracted by light irradiation – to be transferred to DNA. Earlier, experiments found that DNA, RRNA (ribonucleic acid) or proteins could be transmitted very selectively only to small residues (small modifications such as methyl groups). Nils Klöcker, a student at the Institute of Biochemistry, explains.

As a result of the work, it is now possible to transmit larger residues or changes such as the photo-caging groups that have just been mentioned. It was also possible to clarify the basis of the shift in molecular behavior in collaboration with the structural biologist Prof. Daniel Kümmel, who works also at the Institute of Biochemistry.

With more engineering, the enzymatic cascade embracing photocaging groups can be used to block MTases and release them with light, which is an orthogonal trigger and provides exquisite spatio-temporal control. The study is part of the advancement to incorporate in situ-generated AdoMet analogs in epigenetic studies.

Combining these MATs with other enzymes has potential for future cellular applications. This is an important step for implementing in-situ generated, non-natural substances for other enzymes in epigenetic studies, says coauthor Andrea Rentmeister.