Patent ID: 7250284

Claim:
A purified nucleic acid construct comprising: a gene cassette encoding a modified protein selected from the group consisting of: a modified LuxA comprising an amino acid sequence in its carboxy terminus that specifically binds to a tail-specific protease, and a modified LuxB comprising a PEST sequence in its carboxy terminus that specifically binds to a protein associated with a ubiquitin-proteasome pathway, wherein the amino acid sequence that specifically binds to a tail-specific protease results in a reduced half-life of the modified LuxA protein when expressed in a bacterial cell compared to the half-life of the wild-type form of the LuxA protein when expressed in the bacterial cell, and wherein the PEST sequence results in a reduced half-life of the modified LuxB protein when expressed in a yeast cell compared to the half-life of the wild-type form of the LuxB protein when expressed in the yeast cell.