Question

In E. coli, the primary component of the mismatch repair system is the protein MutS. How does MutS recognize mismatched base pairs?

(a)-It reads the major groove and counts the number of hydrogen bonds to determine if there is correct base pairing.
(b)-When mismatched base pairs are transcribed, MutS edits the RNA transcript to correct the mutation.
(c)-It recognizes purine-purine and pyrimidine-pyrimidine mismatches because they are, respectively, longer and shorter than a purine-pyrimidine pair.
(d)-It identifies hemimethylated base pairs and methylates the unmodified base.
(e)-When subjected to force, mismatched base pairs distort more easily than correctly matched basepairs.

Answer 1

The best answer to the question, given the research found on this particular process in E. Coli specifically, would be: D) It identifies hemimethylated base pairs and methylates the unmodified base.

Step-by-step explanation:

According to research on this pretty complicated topic, in E. Coli specifically, and other gram negative prokaryotes, it has been found that the presence, or absence of methylation will initiate MutS, which is a protein both in prokaryotes and eukaryotes responsible, in a full complex, of initiating and carrying out the full mechanism of DNA mismatch repair. As the daughter DNA strands are produced from parent strands, these first ones arise with several deletions and mismatches which need to be repaired and they are recognized due to the fact that daughter strands are hemimethylated. This circumstance activates MutS in E. Coli, who will then bind to the DNA strand that needs to be repaired and together with other members of the complex, like MutH and MutL, begin the process of repair.

In eukaryotes and other prokaryotes, the exact process by which DNA is repaired by MutS is still not totally known.