| Products/Services Used | Details | Operation |
|---|---|---|
| Bacterial Expression System | E. coli strain BL21 Star (DE3) (Invitrogen) was transformed with plasmid pET21-H6-TEV-Q21, encoding N-hexahistidine-tagged, tobacco-etch-virus-protease-site-tagged Q21 under control of the bacteriophage T7 gene 10 promoter [constructed by replacing the NdeI-SalI segment of plasmid pET21a (EMD Millipore) with an NdeI-SalI segment of a synthetic DNA fragment (Genscript) carrying 5'-CATATGGGACATCACCATCACCATCACGAGAACCTGTACTTCCAATCC-3', followed by codons 2-162 of gene Q of lambdoid bacteriophage 21 (1), followed by 5'-GAGTCGAC-3'] | Get A Quote |
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... More
