Precision Genetic Regulatory Elements
New versions of the LacI repressor protein with increased DNA binding affinity. The lac repressor protein (LacI) is a genetic regulatory protein widely used to control the expression of cloned genes and is the prototype for negative control of transcription initiation in E. coli. The lac system has been used for many commercial purposes that benefit from the inducible control of recombinant protein expression. In the production of pharmaceuticals, LacI is used to regulate the expression of desired protein products, many of which would otherwise have toxic effects on the microorganism utilized in their synthesis. Multiple vector systems are commercially available that employ this repressor protein in cloning genes and overexpressing selected protein products. These systems rely on the ability of the lac repressor to inhibit transcriptional initiation in the absence of an inducer. However, wild-type lac repressor proteins have several limitations. First, wild-type LacI allows a low level of constitutive expression that hinders the regulation of toxic proteins. Also, the most widely used LacI inducer, IPTG, is expensive (~$40/g). Rice researchers in Biochemistry and Cell Biology have developed altered lac repressor proteins that allow enhanced regulation of protein expression. The recombinant proteins are comprised either of: 1. A DNA binding domain that possesses increased binding affinity for the DNA sequence and an inducer binding domain of the natural lac repressor protein; or 2. A wild-type DNA binding domain and an inducer binding domain with enhanced responsivity to IPTG; or 3. A DNA binding domain with increased binding affinity for the DNA sequence and an inducer binding domain with enhanced responsivity to IPTG As a clear advancement over the current lac regulation system, these novel genetic switches can be used to improve fermentation processes where tight control of a gene is necessary for optimum efficiency or yield. Further, the increased responsivity to IPTG induction has the potential to reduce one of the most expensive costs of LacI regulation by up to 10-fold. Please contact us for more information on using this technology in your company's manufacturing processes.
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