Structural basis of ECF-sigma-factor-dependent transcription initiation.
Lin, W., Mandal, S., Degen, D., Cho, M.S., Feng, Y., Das, K., Ebright, R.H.(2019) Nat Commun 10: 710-710
- PubMed: 30755604 
- DOI: https://doi.org/10.1038/s41467-019-08443-3
- Primary Citation of Related Structures:  
6DV9, 6DVB, 6DVC, 6DVD, 6DVE - PubMed Abstract: 
Extracytoplasmic (ECF) σ factors, the largest class of alternative σ factors, are related to primary σ factors, but have simpler structures, comprising only two of six conserved functional modules in primary σ factors: region 2 (σR2) and region 4 (σR4). Here, we report crystal structures of transcription initiation complexes containing Mycobacterium tuberculosis RNA polymerase (RNAP), M. tuberculosis ECF σ factor σ L , and promoter DNA. The structures show that σR2 and σR4 of the ECF σ factor occupy the same sites on RNAP as in primary σ factors, show that the connector between σR2 and σR4 of the ECF σ factor-although shorter and unrelated in sequence-follows the same path through RNAP as in primary σ factors, and show that the ECF σ factor uses the same strategy to bind and unwind promoter DNA as primary σ factors. The results define protein-protein and protein-DNA interactions involved in ECF-σ-factor-dependent transcription initiation.
Organizational Affiliation: 
Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ, 08854, USA.