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Crystal structures of the GCaMP calcium sensor protein reveal the mechanism of fluorescence signal change and aid rational design
Author(s) -
Schreiter Eric Robert,
Akerboom Jasper,
Vélez Rivera Jonathan D.,
Rodríguez Guilbe María M.,
Alfaro Malavé Elisa C.,
Hernandez Hector H.,
Tian Lin,
Hires S. Andrew,
Marvin Jonathan S.,
Looger Loren L.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.517.1
Subject(s) - dimer , biophysics , calcium , mutant , fluorescence , signal (programming language) , chemistry , calcium imaging , noise (video) , point mutation , mutation , crystallography , biochemistry , biology , physics , computer science , optics , gene , organic chemistry , artificial intelligence , image (mathematics) , programming language
The genetically encoded calcium indicator (GECI) protein GCaMP2 shows promise for neural network activity imaging, but is currently limited by low signal‐to‐noise ratio. We describe X‐ray crystal structures 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. Based on these structures, we engineered a series of GCaMP2 point mutants and characterized one mutant with significantly improved signal‐to‐noise. The mutation is located at a domain interface and its effect on sensor function could not have been predicted in the absence of structural data.