Spectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus

TitleSpectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus
Publication TypeJournal Article
Year of Publication2014
AuthorsBomati E.K, Haley J.E, Noel J.P, Deheyn DD
JournalScientific Reports
Date Published2014/06
Type of ArticleArticle
ISBN Number2045-2322
Accession NumberWOS:000338101800004
Keywordsaequorea; biosensors; branchiostoma-lanceolatum; chromophore formation; coral; crystallography; gfp-like proteins; model; molecular-basis; to-red conversion

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.

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