The PBAD promoter drives expression of which gene on this plasmid?

The PBAD promoter drives expression of which gene on this plasmid?

• A. RFP
• B. GFP
• C. LacZ
• D. CAT

Answer: (A)

PBAD is an arabinose-inducible promoter that depends on AraC to turn on transcription. In the absence of arabinose, expression is minimal; when arabinose is present, AraC changes conformation and activates transcription of the downstream gene. On this plasmid, the gene placed downstream of PBAD is red fluorescent protein, so inducing with arabinose brings about red fluorescence. The other proteins listed (green fluorescent protein, LacZ, CAT) are not driven by PBAD on this plasmid, but by different promoters elsewhere in the construct.

PBAD is an arabinose-inducible promoter that depends on AraC to turn on transcription. In the absence of arabinose, expression is minimal; when arabinose is present, AraC changes conformation and activates transcription of the downstream gene. On this plasmid, the gene placed downstream of PBAD is red fluorescent protein, so inducing with arabinose brings about red fluorescence. The other proteins listed (green fluorescent protein, LacZ, CAT) are not driven by PBAD on this plasmid, but by different promoters elsewhere in the construct.