Structural insights into stressosome assembly

IUCrJ

Seung Sik Lee¹  Hyeongseop Jeong²  Eunju Kwon³  Pawan Dahal³  Deepak Pathak³  Dong Young Kim³  Hyeun Wook Chang³  Dooil Jeoung⁴  Han-ul Kim⁴  Hyun Suk Jung⁴  Sung Chul Ha⁵ 

[1] Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 56212, Republic of Korea;Center for Electron Microscopy Research, Korea Basic Science Institute, Ochang 28119, Republic of Korea;College of Pharmacy, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Republic of Korea;Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea;Pohang Accelerator Laboratory (PAL), Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea;

关键词: stressosome;    pseudo-icosahedron;    STAS domain;    crystal structure;    cryo-electron microscopy;    X-ray crystallography;    single-particle cryo-EM;   

DOI  :  10.1107/S205225251900945X

来源: DOAJ

【 摘 要 】

The stressosome transduces environmental stress signals to SigB to upregulate SigB-dependent transcription, which is required for bacterial viability. The stressosome core is composed of RsbS and at least one of the RsbR paralogs. A previous cryo-electron microscopy (cryo-EM) structure of the RsbRA–RsbS complex determined under a D2 symmetry restraint showed that the stressosome core forms a pseudo-icosahedron consisting of 60 STAS domains of RsbRA and RsbS. However, it is still unclear how RsbS and one of the RsbR paralogs assemble into the stressosome. Here, an assembly model of the stressosome is presented based on the crystal structure of the RsbS icosahedron and cryo-EM structures of the RsbRA–RsbS complex determined under diverse symmetry restraints (nonsymmetric C1, dihedral D2 and icosahedral I envelopes). 60 monomers of the crystal structure of RsbS fitted well into the I-restrained cryo-EM structure determined at 4.1 Å resolution, even though the STAS domains in the I envelope were averaged. This indicates that RsbS and RsbRA share a highly conserved STAS fold. 22 protrusions observed in the C1 envelope, corresponding to dimers of the RsbRA N-domain, allowed the STAS domains of RsbRA and RsbS to be distinguished in the stressosome core. Based on these, the model of the stressosome core was reconstructed. The mutation of RsbRA residues at the binding interface in the model (R189A/Q191A) significantly reduced the interaction between RsbRA and RsbS. These results suggest that nonconserved residues in the conserved STAS folds between RsbS and RsbR paralogs determine stressosome assembly.

【 授权许可】

Unknown