Patent ID: 7504216

Claim:
A method for determining whether a test DNA molecule interacts with a test polypeptide, the method comprising (a) providing a first population of prokaryotic host cells, wherein at least one of the host cells comprises; (i) a reporter vector comprising a selectable reporter gene and a counterselectable reporter gene, wherein the selectable reporter gene and the counterselectable reporter gene are both operably linked to a test DNA molecule; and (ii) a chimeric gene that encodes a fusion protein comprising a test polypeptide fused to a gene activating domain, wherein interaction of the test DNA molecule and the test polypeptide in the host cell results in an increase in expression of the selectable reporter gene and of the counterselectable reporter gene; (b) maintaining the first population of host cells under selective conditions that allow cell growth as a result of the expression of the selectable reporter gene; (c) isolating the reporter vectors from cells of the first population of host cells that grow under the selective conditions; (d) introducing the isolated reporter vectors into a second population of host cells that lack the chimeric gene; (e) maintaining the second population of host cells under counterselective conditions that inhibit cell growth as a result of the expression of the counterselectable reporter gene; and (f) measuring growth of the second population of host cells, wherein an ability to survive under counterselective conditions indicates that the test DNA molecule has interacted with the test polypeptide.