4 research outputs found
A blue light receptor that mediates RNA binding and translational regulation
Sensory photoreceptor proteins underpin light-dependent adaptations in nature and enable the optogenetic control of organismal behavior and physiology. We identified the bacterial light-oxygen-voltage (LOV) photoreceptor PAL that sequence-specifically binds short RNA stem loops with around 20 nM affinity in blue light and weaker than 1 µM in darkness. A crystal structure rationalizes the unusual receptor architecture of PAL with C-terminal LOV photosensor and N-terminal effector units. The light-activated PAL–RNA interaction can be harnessed to regulate gene expression at the RNA level as a function of light in both bacteria and mammalian cells. The present results elucidate a new signal-transduction paradigm in LOV receptors and conjoin RNA biology with optogenetic regulation, thereby paving the way toward hitherto inaccessible optoribogenetic modalities
Light-Dependent Control of Bacterial Expression at the mRNA Level
Sensory photoreceptors mediate numerous light-dependent
adaptations
across organisms. In optogenetics, photoreceptors achieve the reversible,
non-invasive, and spatiotemporally precise control by light of gene
expression and other cellular processes. The light-oxygen-voltage
receptor PAL binds to small RNA aptamers with sequence specificity
upon blue-light illumination. By embedding the responsive aptamer
in the ribosome-binding sequence of genes of interest, their expression
can be downregulated by light. We developed the pCrepusculo and pAurora
optogenetic systems that are based on PAL and allow to down- and upregulate,
respectively, bacterial gene expression using blue light. Both systems
are realized as compact, single plasmids that exhibit stringent blue-light
responses with low basal activity and up to several 10-fold dynamic
range. As PAL exerts light-dependent control at the RNA level, it
can be combined with other optogenetic circuits that control transcription
initiation. By integrating regulatory mechanisms operating at the
DNA and mRNA levels, optogenetic circuits with emergent properties
can thus be devised. As a case in point, the pEnumbra setup permits
to upregulate gene expression under moderate blue light whereas strong
blue light shuts off expression again. Beyond providing novel signal-responsive
expression systems for diverse applications in biotechnology and synthetic
biology, our work also illustrates how the light-dependent PAL-aptamer
interaction can be harnessed for the control and interrogation of
RNA-based processes