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. Author manuscript; available in PMC: 2023 Jun 5.
Published in final edited form as: Nat Protoc. 2022 Feb 23;17(4):941–961. doi: 10.1038/s41596-021-00657-4

Figure 1.

Figure 1.

General schematic of bacterial two- and three-hybrid systems. a, Schematic of the B2H system. Protein moiety B(ait) is fused to the bacteriophage λ CI protein (λCI) and protein moiety P(rey) is fused to the N-terminal domain of the α subunit of RNAP (α-NTD). Interaction between Bait and Prey proteins activates transcription from the test promoter directing transcription of a lacZ reporter gene on a single copy F’ episome. b, Schematic of the B3H system. RNA moiety B(ait) is fused to the MS2 RNA hairpin (MS2hp) and the protein moiety P(rey) is fused to the α-NTD as in a. The MS2hp-binding moiety MS2 coat protein (MS2CP) is fused to λCI to create a DNA-RNA adapter protein that tethers the RNA Bait upstream of the test promoter. Interaction between Bait RNA and Prey protein activates transcription of the same reporter system used in the B2H assay shown in (a).