You have isolated an E. coli mutant that is abnormal for regulation of the trp operon. The mutation is located close to the structural genes for enzymes involved in tryptophan biosynthesis but is not in any of the structural genes. Initiation of trp operon transcription is repressible in this mutant just like wild type, but this mutant expresses trp structural genes at higher levels than wild type when tryptophan is absent from the medium. Which of the following hypotheses is the best explanation for the mutation?

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asked Nov 23, 2012 in Genetics by GeneX ~Top Expert~ (7,947 points)
    

1 Answer

+1 vote

The mutation is a gain of function mutation in the promoter.

The mutation prevents the leader sequence stem loop involving regions 3 and 4 from forming.

answered Nov 23, 2012 by GeneX ~Top Expert~ (7,947 points)

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