Correct option is D
Explanation-
Option a - "Presence of the σ subunit along with α₂ββ′ω core RNA polymerase is required for its promoter-specific binding." - CORRECT
The core enzyme (α₂ββ′ω) lacks specificity for promoter regions. The σ (sigma) subunit enables specific binding to promoter sequences (like -10 and -35 regions). The complete enzyme (holoenzyme) = core enzyme + σ → needed for transcription initiation.
Option b - "Presence of the σ subunit along with α₂ββ′ω core RNA polymerase is not necessary for the core RNA polymerase to bind to the DNA template." - CORRECT
The core enzyme (without σ) can bind to nonspecific DNA but cannot initiate transcription from specific promoters. So, σ is not required for DNA binding, but for promoter recognition.
Option c - "Mutations in β subunit in its rifampicin resistance defining region (RRDR) confer rifampicin resistance phenotype." - CORRECT
Rifampicin is an antibiotic that inhibits RNA polymerase activity by binding to the β subunit. Mutations in the RRDR (Rifampicin Resistance Determining Region) of the β subunit prevent rifampicin from binding → causing resistance.
Option d - "Mutations in σ subunit in its rifampicin resistance defining region (RRDR) confer rifampicin resistance phenotype." - INCORRECT
The σ subunit is not the target of rifampicin. Rifampicin binds to the β subunit, not σ. Therefore, mutations in the σ subunit do NOT confer rifampicin resistance. RRDR is a specific region in the β subunit, not in σ.
Final Answer: Option d is incorrect, making it the correct choice for the question asking which one is NOT a correct feature of E. coli RNA polymerase.
