Crystal structures of the GCaMP calcium sensor reveal the mechanism of fluorescence signal change and aid rational design.

ABSTRACT: The genetically encoded calcium indicator GCaMP2 shows promise for neural network activity imaging, but is currently limited by low signal-to-noise ratio. We describe x-ray crystal structures as well as solution biophysical and spectroscopic characterization of GCaMP2 in the calcium-free dark state, and in two calcium-bound bright states: a monomeric form that dominates at intracellular concentrations observed during imaging experiments and an unexpected domain-swapped dimer with decreased fluorescence. This series of structures provides insight into the mechanism of Ca2+-induced fluorescence change. Upon calcium binding, the calmodulin (CaM) domain wraps around the M13 peptide, creating a new domain interface between CaM and the circularly permuted enhanced green fluorescent protein domai

SUBMITTER: Akerboom J 

PROVIDER: S-EPMC2649101 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature