Methods for controlling gene expression in cells and thus the production of proteins are of great importance for applied and fundamental research. For some years now, in addition to established approaches involving the addition of chemical substances, it has also been possible to control gene expression using light irradiation. This approach, known as optogenetics, has so far been based almost exclusively on activating the transcription of DNA into mRNA (messenger RNA). However, the study by the Photobiochemistry group at the University of Bayreuth goes one step further: the researchers established a new optogenetic approach, dubbed riboptoregulator, to activate bacterial gene expression at the mRNA level using blue light. The advantages of controlling gene expression at the mRNA level include the speed of the response, modularity and combinability with other genetic circuits.
The team led by Prof. Dr. Andreas Möglich used the photoreceptor PAL, which they already discovered a few years ago. Upon activation with blue light, PAL can bind specific RNA structures and release a blockade at the so-called translation initiation region. Ribosomes, which are responsible for translating the mRNA into proteins, dock onto this region. Once the blockade has been released by PAL, the mRNA can be translated.
“We exploited the modularity of the riboptoregulator module and combined it with other genetic circuits to establish the new pAurora2 system. The resultant, integrated setup controls bacterial gene expression in response to blue light in a particularly stringent manner and surpasses previous approaches,” says Möglich. The pAurora2 system is so efficient because it promotes gene expression at two points: Firstly, pAurora2 releases the blockade of translation of the target gene on the mRNA strand, and secondly, the system suppresses the expression of a translation repressor. In this way, the expression of a target gene can be boosted over 1,000-fold.
“This regulation at the RNA level brings many advantages that in the future can be used for modern applications of light-regulated bacterial gene expression in theranostics, biotechnology or materials science,” says Dr. Américo Ranzani, first author of the study and a postdoc in the Photobiochemistry research group at the time it was carried out.
The research project was funded by the German Research Foundation (DFG) (MO2192/6-2 and MO2192/10-1).
