6IVU

Solution structure of the Sigma-anti-sigma factor complex RsgI1N-SigI1C from Clostridium thermocellum

Summary for 6IVU

• Entry DOI: 10.2210/pdb6ivu/pdb
• Related: 6IVS
• NMR Information: BMRB: 36221
• Descriptor: Anti-sigma-I factor RsgI1, RNA polymerase sigma factor SigI1 (2 entities in total)
• Functional Keywords: sigma factor, transcription
• Biological source: Hungateiclostridium thermocellum ATCC 27405 (Ruminiclostridium thermocellum); More
• Total number of polymer chains: 2
• Total formula weight: 20396.84

Authors

Wei, Z.,Feng, Y. (deposition date: 2018-12-04, release date: 2019-05-15, Last modification date: 2024-05-15)

Primary citation

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.
Alternative sigma I/anti-sigma I factors represent a unique form of bacterial sigma /anti-sigma complex.
Nucleic Acids Res., 47:5988-5997, 2019

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.

PubMed: 31106374
DOI: 10.1093/nar/gkz355

Experimental method

SOLUTION NMR