Controlling Biological Processes with Light: New Insights into Bacterial Signaling Pathways
Controlling Biological Processes with Light: New Insights into Bacterial Signaling Pathways
2 July 2026
Researchers at Forschungszentrum Jülich and the University of Bayreuth have uncovered how certain light-sensitive enzymes transmit signals in bacteria. The findings could help develop new tools for specifically controlling biological processes using light. This is particularly interesting for applications in biotechnology and medical research. The study was published in the journal Science Advances.
The focus is on so-called sensor histidine kinases (SHKs). These proteins function like tiny switches: they detect signals from their environment and trigger reactions within the cell. Depending on the signal, they transfer phosphate groups to other proteins or remove them again. Some SHKs respond to light and are already used in optogenetics. This field of research uses light to specifically control processes within cells. A better understanding of the underlying mechanisms could help develop such tools in a more targeted manner in the future.
How light switches an enzyme
Until now, little was known about how SHKs transmit light signals within the protein. The research team from Jülich and Bayreuth therefore investigated newly developed light-sensitive SHKs and compared their structure with their function.
The investigated sensor histidine kinase can switch between a kinase and a phosphatase form in response to blue light. In doing so, it either transfers phosphate groups to other proteins or removes them. The stylized protein structures show spatial arrangement of the protein in the two states. Protein crystals used for the structural analyses are shown in the background.Copyright: Ulrich Krauss (Universität Bayreuth) / Renu Batra-Safferling (Forschungszentrum Jülich)
“In our study, we examined new, artificially created light-sensitive SHKs—which can be used as optogenetic tools—both structurally and functionally. In doing so, we combined crystal structure data with analyses of the proteins in solution and functional tests,” says Ulrich Krauss from the Chair of Biochemistry I at the University of Bayreuth and a visiting scientist at the Institute for Molecular Enzyme Technology at Heinrich Heine University Düsseldorf, which is also part of the Jülich Institute for Bio- and Geosciences IBG-1.
The researchers were able to show that the enzymes adopt different shapes depending on whether they are in the dark or exposed to light. In the dark, they have an asymmetrical, slightly bent structure. Light, on the other hand, promotes a symmetrical, straight shape.
Form Determines Function
This structural change determines which signals are transmitted within the cell. The investigations suggest that the bent form promotes the transfer of phosphate groups to other proteins, such as regulators, while the straight form removes them.
“Simply put, in the asymmetric form, key parts of the enzyme are oriented relative to one another in a way that enables kinase activity. The switch to the symmetric, straight form alters this arrangement and makes the components incompatible for kinase function. This favors phosphatase activity over kinase activity,” adds Krauss.
Foundation for new optogenetic tools
The results provide important insights into how light-sensitive proteins transmit signals. This knowledge can help in the targeted development of optogenetic tools to control biological processes even more precisely with light in the future.
“Close collaboration between various institutes and research groups at Forschungszentrum Jülich and the University of Bayreuth was crucial for deciphering the mechanism of signal transmission,” says Batra-Safferling.
The study was conducted as part of the OptoSys project (FKZ 031A166 and FKZ 031A167B), funded by the Federal Ministry of Education and Research (BMBF), and was supported by the German Research Foundation (DFG).
Original publication
Vladimir Arinkin, Andreas M. Stadler, Stefanie S.M. Meier, Karl-Erich Jaeger, Andreas Möglich, Ulrich Krauss, Renu Batra-Safferling. Dimer asymmetry in signaling of blue-light sensor histidine kinases. Science Advances (2026) DOI: 10.1126/sciadv.aed8943
