Question

ΦC31 is a type of bacteriophage that infects
Streptomyces bacteria. One gene in the bacteriophage
genome specifies a recombinase called ΦC31 integrase that works through a mechanism slightly different from that of the recombinase shown in Fig. 6.30.
Most importantly, the two target DNA sequences are
different from each other. One called attP is 39 base
pairs and is found on the circular bacteriophage chromosome, while the other—attB—is 34 base pairs
long and is located on the much larger circular bacterial chromosome. Excepting two base pairs roughly
in the middle of both targets that are identical and
at which recombination takes place, the DNA
sequences of attP and attB are completely different
from each other.
a. Diagram the reaction that ΦC31 integrase performs. How could this reaction be important for
the life cycle of the bacteriophage?
b. Using the diagram you just drew, explain why
ΦC31 integrase cannot reverse the reaction.
c. Now consider how you might exploit this sitespecific recombination to place genes from another
species (a transgene) into the genome of an experimental organism like Drosophila. Assume you can
make any DNA sequences you want and that you
can introduce these DNA sequences into fruit fly germ-line cells by injection. Why is the irreversibility of the ΦC31 integrase–mediated reaction
valuable for placing the transgene into the
Drosophila genome?
d. Bacteriophage ΦC31 must eventually reverse this
reaction. Why? How do you think the bacteriophage can achieve this reversal?

Answer 1

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Hope it's clear..thanks