A 58-year-old female is admitted to the hospital with fever, abdominal cramps, and severe watery diarrhea. The symptoms began one day after attending a banquet. She was treated with ciprofloxacin, but her condition did not improve. PCR amplification and analysis of a gene region in the bacteria isolated from the patient revealed a missense mutation that conferred resistance to ciprofloxacin. The missense mutation is most likely in the gene encoding an enzyme essential for which of the following functions?

1. A)DNA replicationGABARITO
2. B)Reduction of folate to tetrahydrofolate
3. C)Peptide bond formation
4. D)mRNA translocation on a ribosome
5. E)Folate synthesis