Fluorescent properties and photostability of streptavidin-conjugated StayGOLD protein for DNA labeling

Abstract

Here, we report a strepatavidin(SA)-conjugated StayGOLD fluorescent protein as a DNA labeling agent. We investigate the photophysical properties and photostability of the streptavidin-coupled StayGOLD fluorescent protein compared to SA-mNeonGreen. Fluorescent proteins, particularly StayGOLD variants, are recognized for their enhanced stability and brightness, making them suitable for prolonged imaging. Using SA-StayGOLD in DNA labeling, we observed significant improvements in fluorescence intensity and reduced photobleaching relative to SA-mNeonGreen. Photophysical analyses suggest that StayGOLD's stability arises from specific structural features, including interactions of protein residues and water molecules with the chromophore. Structural comparisons revealed differing chromophore environments between SA-StayGOLD and SA-mNeonGreen, with arginine (R86) in StayGOLD appearing as a particularly relevant factor for its photostability. These findings confirm SA-StayGOLD as a superior tool for single-molecule DNA imaging, where high fluorescence intensity and photostability are essential for data quality.