Artificial Allosteric Control of Proteins

We built an artificial mechanism of allosteric control of a protein, based on mechanical stress. The Maltose-Binding Protein (MBP) of E. coli undergoes a conformational change upon binding maltose. Introducing a mechanical stress favoring one or the other conformation will therefore alter the binding affinity for the substrate. We have constructed a chimera where the two lobes of the maltose binding protein are covalently coupled to the ends of a DNA oligomer. The mechanical tension on the protein is provided by the bending elasticity of the DNA, and is controlled by exploiting the difference between single stranded and double stranded DNA. We report that the binding affinity of MBP for maltose is significantly altered by the tension, which was varied by allowing DNA oligomers of various lengths to hybridize to the DNA of the chimera. By the same method, we control the enzymatic activity of a second protein: Guanylate Kinase from Mycobacterium Tuberculosis. This study exemplifies a general strategy to introduce artificial control elements in the function of proteins.