Comparison of monomeric variants of StayGold

Abstract

StayGold is a bright and highly photostable fluorescent protein (FP) that forms an obligate dimer, thereby limiting its application as a soluble marker. On the basis of the structural information of this FP, we disrupted the dimerization to generate a monomeric variant, mStayGold, which inherits both the extremely high photostability and the high practical brightness of StayGold, for molecular fusion and membrane-targeting applications. Meanwhile, two other research groups have independently monomerized StayGold using different strategies. As a result, multiple StayGold monomers are currently available, creating confusion in the research community. In the present study, we investigated the three basic properties--photostability, brightness, and dispersibility--of these monomers by performing detailed side-by-side comparisons. This study highlights the difficulties of StayGold monomerization with emphasis on the tradeoff between photostability and brightness in FP technology.