title: Spectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus.
abstract: The cephalochordate Amphioxus naturally co-expresses fluorescent proteins (FPs) with different brightness, which thus offers the rare opportunity to identify FP molecular feature/s that are associated with greater/lower intensity of fluorescence. Here, we describe the spectral and structural characteristics of green FP (bfloGFPa1) with perfect (100%) quantum efficiency yielding to unprecedentedly-high brightness, and compare them to those of co-expressed bfloGFPc1 showing extremely-dim brightness due to low (0.1%) quantum efficiency. This direct comparison of structure-function relationship indicated that in the bright bfloGFPa1, a Tyrosine (Tyr159) promotes a ring flipping of a Tryptophan (Trp157) that in turn allows a cis-trans transformation of a Proline (Pro55). Consequently, the FP chromophore is pushed up, which comes with a slight tilt and increased stability. FPs are continuously engineered for improved biochemical and/or photonic properties, and this study provides new insight to the challenge of establishing a clear mechanistic understanding between chromophore structural environment and brightness level.
authors: Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037 USA.
authors: Erin K
authors: EK
authors: Bomati
authors: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433.
authors: Joy E
authors: JE
authors: Haley
authors: Howard Hughes Medical Institute, Salk Institute for Biological Studies, Jack H. Skirball Center for Chemical Biology and Proteomics, La Jolla, CA 92037.
authors: Joseph P
authors: JP
authors: Noel
authors: Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037 USA.
authors: Dimitri D
authors: DD
authors: Deheyn
mesh_terms: D000818:Animals; D003460:Crystallization; D018360:Crystallography, X-Ray; D005453:Fluorescence; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*; D064175:Lancelets / Q000378:metabolism*; D008958:Models, Molecular; D017510:Protein Folding
chemical_list: D049452:Green Fluorescent Proteins