A method for Absolute Protein Expression Quantity Measurement Employing Insulator RiboJ

Measuring the absolute protein expression quantity for a specific promoter is necessary in the fields of both molecular biology and synthetic biology.The strength of a promoter is traditionally characterized by measuring the fluorescent intensity of the fluorescent protein downstream of the promoter.Until now,measurement of the absolute protein expression quantity for a promoter,however,has been unsuccessful in synthetic biology.The fact that the protein coding sequence influences the expression level for different proteins,and the inconvenience of measuring the absolute protein expression level,present a challenge to absolute quantitative measurement.Here,we introduce a new method that combines the insulator RiboJ with the standard fluorescence curve in order to measure the absolute protein expression quantity quickly;this method has been validated by modeling verification.Using this method,we successfully measured nine constitutive promoters in the Anderson promoter family.Our method provides data with higher accuracy for pathway design and is a straightforward way to standardize the strength of different promoters.

Identification of the Decay Pathway of Photoexcited Nucleobases

The identification of the decay pathway of the nucleobase uracil after being photoexcited by ultraviolet light has been a long-standing problem.Various theoretical models have been proposed but yet to be verified.Here,we propose an experimental scheme to test the theoretical models of gas phase uracil decay mechanism by a combination of ultrafast x-ray spectroscopy,x-ray diffraction,and electron diffraction methods.Incorporating the signatures of multiple probing methods,we demonstrate an approach that can identify the dominant mechanism of the geometric and electronic relaxation of the photoexcited uracil molecule among several candidate models.