Development of a reporter peptide that catalytically produces a fluorescent signal through α-complementation.

In α-complementation, inactive N-terminal (α-domain) and C-terminal (ω-domain) fragments of β-galactosidase associate to reconstitute the active protein. To date, the effect of α-domain size on α-complementation activity has not been systematically investigated. In this study, we compared the complementation activities of α-domains of various sizes using an in vitro system. We found that the complementation activities are similar for α-domains comprising between 45 and 229 N-terminal residues but are significantly decreased for those containing less than 37 residues. However, these smaller α-domains (15 and 25 residues) exhibited sufficient α-complementation activity for application as reporters.