What cellular effect does the inhibition of dihydrofolate reductase have on bacteria?

Inhibition of dihydrofolate reductase in bacteria leads to a decrease in nucleotide synthesis. Dihydrofolate reductase is an essential enzyme in the folate pathway, responsible for the reduction of dihydrofolate to tetrahydrofolate, which is a critical cofactor for the synthesis of purines and thymidylate. This process is vital for DNA synthesis and repair.

When dihydrofolate reductase is inhibited, the availability of tetrahydrofolate is reduced, ultimately resulting in impaired synthesis of nucleotides. Consequently, this inhibition leads to reduced DNA replication and cell growth, as nucleotides are the building blocks required for forming DNA.

This mechanism is the basis for the action of certain antibiotics, like trimethoprim, which specifically targets bacterial dihydrofolate reductase and disrupts bacterial proliferation by limiting their ability to synthesize nucleic acids. Hence, the correct impact of inhibiting this enzyme is a decrease in nucleotide synthesis, which impairs the growth and reproduction of bacterial cells.