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304 Serebriiskii et al.Fig. 4. Characterization of bacterial reporter activity using replica technique. (A)Replica techniques. (Top) Pick each bacterial colony (1–2-mm diameter) to be testedfrom the transformation plates, and resuspend it in NM medium 100 µL of sterile ina well of a 96-well microtiter plate. If sterile toothpicks are used for picking colonies,they need to be removed immediately after resuspension of a colony, to preventabsorption of the liquid. Plastic pipet tips can be also used; place an insert (as indicatedby ref. 1) from a rack of pipet tips (e.g., Rainin RT series) over the top of themicrotiter plate, and attach to the sides of the plate using tape (shown in ref. 2).(Bottom) After removal of the tips, a metal replicator is used as described in the textto transfer colonies to selection plates. (B) Typical results on selection plates. Hereinpotential H-Ras interactors from a Bacteriomatch HeLa library are analyzed. Patcheswere obtained after printing of the bacterial suspension on various selection plates(see Note 13 for using replica tool). The NM_TC medium is nonselective for interaction,whereas use of various concentrations of 3-AT, addition of streptomycin, orthe combination of these approaches represents various selection strengths. Theseare used to identify candidate interactors, as described in Subheading 3.2.2.