Abstract

To study interactions between C_4 -dicarboxylic acid transport protein D and E[sigma]^54 in the dctA promoter regulatory region, we used the challenge phage system. An ant'-'lac fusion was recombined onto the challenge phage, and this ant'-'lac fusion along with Pant and the R. meliloti dctA promoter regulatory region were cloned onto a plasmid. The plasmid bearing the ant'-'lac fusion was used as a reporter plasmid in a coupled transcription-translation system. Addition of purified [sigma]^54 to the coupled system specifically repressed transcription of the plasmid-borne ant'-'lac fusion. When DCTD was added along with [sigma]^54 to the coupled system, transcription of the ant'-'lac fusion was even further repressed, suggesting that DCTD may stabilize closed complexes between E[sigma]^54 and the dctA promoter.

• Keywords: challenge phage system; [sigma]^54 ; dctA; DCTD