Video narration
How can one drug shut down an entire bacterium's production line-like a printer that can't read its template and therefore can't make new pages? Rifampicin enters the bacterial cell and binds DNA-dependent RNA polymerase, the machine that copies information from bacterial DNA. More specifically, it binds the enzyme's β-subunit. That subunit is encoded by the rpoB gene. Normally, RNA polymerase carries out transcription: it reads DNA and produces mRNA. That mRNA supplies the instructions for essential bacterial proteins. Block that machine, and you remove the mRNA supply. No mRNA means no essential protein synthesis. Growth is inhibited, and the bacterium eventually dies. That is the high-yield link. So, what shuts tuberculosis bacteria down? Rifampicin inhibits RNA polymerase, blocks transcription, and cuts off essential proteins. And the exam clue is rpoB: mutations in this gene commonly cause rifampicin resistance.