6P1B

Transcription antitermination factor Q21

Summary for 6P1B

• Entry DOI: 10.2210/pdb6p1b/pdb
• Descriptor: Q protein, CHLORIDE ION, 1,2-ETHANEDIOL, ... (4 entities in total)
• Functional Keywords: rna polymerase, dna binding, transcription, q-dependent antitermination, q antitermination factor, gene regulation
• Biological source: Phage 21
• Total number of polymer chains: 2
• Total formula weight: 37904.93

Authors

Yin, Z.,Ebright, R.H. (deposition date: 2019-05-19, release date: 2019-06-26, Last modification date: 2023-10-11)

Primary citation

Yin, Z.,Kaelber, J.T.,Ebright, R.H.
Structural basis of Q-dependent antitermination.
Proc.Natl.Acad.Sci.USA, 116:18384-18390, 2019

PubMed Abstract: Lambdoid bacteriophage Q protein mediates the switch from middle to late bacteriophage gene expression by enabling RNA polymerase (RNAP) to read through transcription terminators preceding bacteriophage late genes. Q loads onto RNAP engaged in promoter-proximal pausing at a Q binding element (QBE) and adjacent sigma-dependent pause element (SDPE) to yield a Q-loading complex, and Q subsequently translocates with RNAP as a pausing-deficient, termination-deficient Q-loaded complex. Here, we report high-resolution structures of 4 states on the pathway of antitermination by Q from bacteriophage 21 (Q21): Q21, the Q21-QBE complex, the Q21-loading complex, and the Q21-loaded complex. The results show that Q21 forms a torus, a "nozzle," that narrows and extends the RNAP RNA-exit channel, extruding topologically linked single-stranded RNA and preventing the formation of pause and terminator hairpins.

PubMed: 31455742
DOI: 10.1073/pnas.1909801116

Experimental method

X-RAY DIFFRACTION (1.942 Å)