Bacteriophage 933W, GpQ / Phage antitermination protein Q / negative regulation of termination of DNA-templated transcription / DNA binding / Q protein
National Institutes of Health/National Institute of Environmental Health Sciences (NIH/NIEHS)
GM041376
米国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2019 タイトル: Structural basis of Q-dependent antitermination. 著者: Zhou Yin / Jason T Kaelber / Richard H Ebright / 要旨: 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 ...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.