Download MendeleyAlternative sigma I/anti-sigma I factors represent a unique form of bacterial sigma /anti-sigma complex.
Wei, Z., Chen, C., Liu, Y.J., Dong, S., Li, J., Qi, K., Liu, S., Ding, X., Ortiz de Ora, L., Munoz-Gutierrez, I., Li, Y., Yao, H., Lamed, R., Bayer, E.A., Cui, Q., Feng, Y.(2019) Nucleic Acids Res 47: 5988-5997
- PubMed: 31106374
- DOI: https://doi.org/10.1093/nar/gkz355
- Primary Citation of Related Structures:
6IVS, 6IVU - PubMed Abstract:
The σ70 family alternative σI factors and their cognate anti-σI factors are widespread in Clostridia and Bacilli and play a role in heat stress response, virulence, and polysaccharide sensing. Multiple σI/anti-σI factors exist in some lignocellulolytic clostridial species, specifically for regulation of components of a multienzyme complex, termed the cellulosome. The σI and anti-σI factors are unique, because the C-terminal domain of σI (SigIC) and the N-terminal inhibitory domain of anti-σI (RsgIN) lack homology to known proteins. Here, we report structure and interaction studies of a pair of σI and anti-σI factors, SigI1 and RsgI1, from the cellulosome-producing bacterium, Clostridium thermocellum. In contrast to other known anti-σ factors that have N-terminal helical structures, RsgIN has a β-barrel structure. Unlike other anti-σ factors that bind both σ2 and σ4 domains of the σ factors, RsgIN binds SigIC specifically. Structural analysis showed that SigIC contains a positively charged surface region that recognizes the promoter -35 region, and the synergistic interactions among multiple interfacial residues result in the specificity displayed by different σI/anti-σI pairs. We suggest that the σI/anti-σI factors represent a distinctive mode of σ/anti-σ complex formation, which provides the structural basis for understanding the molecular mechanism of the intricate σI/anti-σI system.
Organizational Affiliation:
CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
