I am doing genetics assignment for my microbiology class whe

I am doing genetics assignment for my microbiology class, where i have to write two hypothesises. we were given the gene (gyr A) that was mutated during experiment of the two species (D. vulgaris and M. maripaludis). I just have to write hypothesis and how i would test it. I don\'t really have to carry out the experiment. any helps would be appreciated.

\"Write two hypotheses about how mutatDNA gyrase subunit A might affect the fitness of D. vulgaris or M. maripaludis in its evolution environment. What experiment or experiments could you do to distinguish between these hypotheses\"

Solution

The topoisomerase class of enzymes called DNA gyrase in bacteria is essential for replication of circular DNA and separating the daughter strands. The two subunits of DNA gyrase, encoded by gyrA and gyrB, helps in the introduction of negative superhelicity in the DNA strands during replication while removing the positive coiling. In some species, DNA gyrase also helps in decatenation, that is the separation of the two intertwined daughter DNA strands in the form of catenane.

If DNA gyrase gene gyrA is mutated, there might be two consequences:

A class of chemicals known as quinolones are Gyr A inhibitors and abolishes DNA supercoiling. If gyrA gene is mutated in a bacteria, then upon the action of quinolones, DNA cleavage and relaxation will not be visible.

Hypothesis

Effect of quinolone (inhibitor of gyrA) on mutant DNA gyrase subunit A of species D. vulgaris or M. maripaludis. The extent of mutation of gyr A and its effect in both the species can be compared by studying the effect of quinolone on the DNA conformation.

If gyr A is essential for DNA supercoiling and decatenation in each species, the quinolone would act on gyrA, but mutated gyr A would inhibit quinolone binding. Upon isolation of DNA from the two species and analyzing the banding pattern on gel electrophoresis, as compared to a standard, it can be interpreted whether the DNA are found as relaxed circular or supercoiled strands.