Light-activated tetanus neurotoxin for conditional proteolysis and inducible synaptic inhibition in vivo.
                            
                                blue
                            
                            
                                AsLOV2
                            
                            
                                
                                    HEK293T
                                
                            
                                
                                    MIN6
                                
                            
                                
                                    mouse hippocampal slices
                                
                            
                                
                                    mouse in vivo
                                
                            
                                
                                    rat cortical neurons
                                
                            
                                
                                    rat hippocampal neurons
                                
                            
                                
                                    S. cerevisiae
                                
                            
                            
                                Neuronal activity control
                            
                            
                            
                            
                            
                        
                        
                        
                        
                            Abstract:
                            The light chain of tetanus neurotoxin (TeNT) is a 52 kD metalloprotease that potently inhibits synaptic transmission by cleaving the endogenous vesicle fusion protein VAMP2. To mitigate the toxicity of TeNT and harness it as a conditional tool for neuroscience, we engineered Light-Activated TeNT (LATeNT) via insertion of the light-sensitive LOV domain into an allosteric site. LATeNT was optimized by directed evolution and shown to have undetectable activity in the dark mammalian brain. Following 30 seconds of weak blue light exposure, however, LATeNT potently inhibited synaptic transmission in multiple brain regions. The effect could be reversed over 24 hours. We used LATeNT to discover an interneuron population in hippocampus that controls anxiety-like behaviors in mouse, and to control the secretion of endogenous insulin from pancreatic beta cells. Synthetic circuits incorporating LATeNT converted drug, Ca2+, or receptor activation into transgene expression or reporter protein secretion. Due to its large dynamic range, rapid kinetics, and highly specific mechanism of action, LATeNT should be a robust tool for conditional proteolysis and spatiotemporal control of synaptic transmission in vivo.