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Structural analysis of the Sulfolobus solfataricus TF55β chaperonin by cryo-electron microscopy.

ABSTRACT: Chaperonins are biomolecular complexes that assist in protein folding. Thermophilic factor 55 (TF55) is a group II chaperonin found in the archaeal genus Sulfolobus that has α, β and γ subunits. Using cryo-electron microscopy, structures of the β-only complex of S. solfataricus TF55 (TF55β) were determined to 3.6-4.2 Å resolution. The structures of the TF55β complexes formed in the presence of ADP or ATP highlighted an open state in which nucleotide exchange can occur before progressing in the refolding cycle.

SUBMITTER: Zeng YC

PROVIDER: S-EPMC7938637 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature

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Structural analysis of the Sulfolobus solfataricus TF55β chaperonin by cryo-electron microscopy.

Zeng Yi Cheng YC Sobti Meghna M Stewart Alastair G AG

Acta crystallographica. Section F, Structural biology communications 20210303 Pt 3

Chaperonins are biomolecular complexes that assist in protein folding. Thermophilic factor 55 (TF55) is a group II chaperonin found in the archaeal genus Sulfolobus that has α, β and γ subunits. Using cryo-electron microscopy, structures of the β-only complex of S. solfataricus TF55 (TF55β) were determined to 3.6-4.2 Å resolution. The structures of the TF55β complexes formed in the presence of ADP or ATP highlighted an open state in which nucleotide exchange can occur before progressing in the r ...[more]

PMID: 33682792

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Project description:The local and global dynamics of the Sulfolobus solfataricus beta-glycosidase were studied by electron spin resonance and time-resolved fluorescence techniques. For electron paramagnetic resonance (EPR) investigations, the protein was covalently modified by the maleimido nitroxide spin label, which is specific for cysteine -SH groups, at position 344 and at position 101, where Ser-101 was changed into a cysteine by site-directed mutagenesis. The greater reactivity of exposed Cys-101 suggested the exclusive modification of this amino acid compared with Cys-344. The labeled proteins underwent temperature perturbation in the range 290-335 K and the values of the spin-label rotation correlation frequencies (nu(c)) ranged from 6 x 10(7) to 2 x 10(8) sec(-1) for the protein labeled at position C344 and from 5.62 x 10(7) to 1.10 x 10(8) sec(-1) for the protein labeled at C101. These rotation correlation values are related to the local dynamic characteristics of the protein matrix. The temperature dependence of rotation correlation frequencies expressed in terms of Arrhenius coordinates (log (nu(c)) vs. 1/T) for the protein labeled at C344 exhibited a linear dependence but with a change in the slope at 311 K. For the protein labeled at C101, no change in the slope was observed at the same temperature. General dynamic information was deduced from the analysis of the fluorescence emission decay of the tryptophanyl residues that are present in each region of the protein structure. Fluorescence data analysis highlighted a bimodal distribution of fluorescence lifetimes arising from the contribution of two emitting groups: one consisting of closely clustered tryptophans responsible for the long-lived emission component (7.1 nsec) and the other composed of tryptophans nearer to the protein surface, which can be associated to the short-lived component (2.5 nsec). The temperature dependence of lifetime distribution parameters linked to the long-lived and short-lived components, expressed in Arrhenius coordinates, showed two different points in which the change in the slope occurred (i.e., 328 K and 338 K, respectively). The Arrhenius analysis of data provided the activation energy relative to the conformational changes characterizing the local and global movements running through the protein matrix.

Dataset Information

Structural analysis of the Sulfolobus solfataricus TF55β chaperonin by cryo-electron microscopy.

Publications

Structural analysis of the Sulfolobus solfataricus TF55β chaperonin by cryo-electron microscopy.

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