Prokaryotic Transcription

Sigma Factor

A protein subunit that binds to RNA polymerase core enzyme to recognize specific promoter elements (-10 and -35) and direct holoenzyme positioning for transcription initiation.

RNA Polymerase Core Enzyme

prokaryotic catalytic complex of alpha (2), beta, beta', and omega subunits. synthesizes RNA 5' —> 3' along a 3' to 5' DNA template strand.

RNA Polymerase Holoenzyme

The complete, functional prokaryotic transcription complex formed by sigma factor and RNA polymerase core.

-35 Consensus Sequence (TTGACA)

A conserved cis-acting promoter DNA element upstream of TSS recognized by the sigma factor. Binding here promotes higher transcription efficiency

-10 Consensus Sequence (Pribnow Box / TATAAT)

A conserved cis-acting promoter DNA element upstream of TSS recognized by the sigma factor. AT-rich and melted to form an open promoter complex.

Intrinsic Transcription Termination

A hairpin-dependent termination mechanism in bacteria where transcript self-complementary G-C rich sequences fold into an RNA hairpin loop that stalls RNA polymerase, followed by a U-rich tract whose weak A-U base pairing causes spontaneous dissociation of the transcript, polymerase, and DNA