Bacterial multidrug resistance (MDR) is a serious and pressing threat to public
ID: 219151 • Letter: B
Question
Bacterial multidrug resistance (MDR) is a serious and pressing threat to public health. The emrRAB operon encodes a pump that can extrude, using proton motive force, several structurally unrelated drugs from Escherichia coli, e.g., protonophores and the antibiotics thiolactomycin and nalidixic acid (NA). The EmrB protein pumps the drugs across the cytoplasmic membrane; EmrA probably facilitates passage through the periplasm; and a third, as yet unidentified protein transports it through the outer membrane. The emrRAB operon, which has a signma70 type promoter, is negatively regulated by the product of one of its own genes, namely, emrR. The pump is induced by a variety of structurally unrelated drugs, many of which are also its substrates. Based on the information above answer the following questions.
1. Fill in the blanks in the DNA with the letter codes that represent the following sequence elements.
5’_ ________emrR ________ emrA ________ emrB ________ _3’
A. Promoter
B. emrR binding site
C. Shine-Dalgarno site
D. Transcription terminator
2. When bound to the drugs (e.g. thiolactomycin), the DNA-binding ability of emrR protein will (explain please):
A. increase.
B. decrease.
C. not change.
D. Cannot tell.
Explanation / Answer
In operons promoter is present which leads to activation of structural genes.
A. promoter.
c. shine dalgarno site.
d. transcription terminator.
2.
not change because it function normally and then do further processing.
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