Towards a Synthetic Biology of Calcium-Regulated Cav Channels

Abstract

Synthetic biology seeks to simplify biological networks and their constitutent molecules into modules amenable to reconfiguration. In this regard, little has yet been achieved for Ca2+ signaling, owing to the seeming irreducible complexity of underlying molecules like CaV channels. In particular, Ca2+ influx through these channels is subject to vital forms of Ca2+ feedback regulation, reliant upon interactions of calmodulin (CaM) with channel elements like the IQ domain (a, black circle). Thwarting simplification, however, has been the utter loss of channel function upon deleting the IQ module (JBC269:1635; JBC275:25436). Here, we report that channels lacking an IQ domain function robustly upon covalent attachment of a single CaM (b). Moreover, the typical Ca2+ regulation of these channels (usually manifest as faster decay of Ca2+ versus Ba2+ current) is absent (c), rendering these channels as a blank regulatory slate. Separately over-expressing the IQ domain strikingly rescues Ca2+ regulation (d), casting the IQ element as a synthetic switch for regulation. These results suggest that CaV channels can be deconstructed into minimal regulatory components, raising the possibility of engineering modular CaV-based Ca2+ signal generators within a synthetic Ca2+ signaling toolkit.View Large Image | View Hi-Res Image | Download PowerPoint Slide