Dataset Information

Human ?B2-Crystallin Forms a Face-en-Face Dimer in Solution: An Integrated NMR and SAXS Study.

ABSTRACT: ??-Crystallins are long-lived eye lens proteins that are crucial for lens transparency and refractive power. Each ??-crystallin comprises two homologous domains, which are connected by a short linker. ?-Crystallins are monomeric, while ?-crystallins crystallize as dimers and multimers. In the crystal, human ?B2-crystallin is a domain-swapped dimer while the N-terminally truncated ?B1-crystallin forms a face-en-face dimer. Combining and integrating data from multi-angle light scattering, nuclear magnetic resonance, and small-angle X-ray scattering of full-length and terminally truncated human ?B2-crystallin in solution, we show that both these ?B2-crystallin proteins are dimeric, possess C2 symmetry, and are more compact than domain-swapped dimers. Importantly, no inter-molecular paramagnetic relaxation enhancement effects compatible with domain swapping were detected. Our collective experimental results unambiguously demonstrate that, in solution, human ?B2-crystallin is not domain swapped and exhibits a face-en-face dimer structure similar to the crystal structure of truncated ?B1-crystallin.

SUBMITTER: Xi Z

PROVIDER: S-EPMC5381515 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Publications

Human βB2-Crystallin Forms a Face-en-Face Dimer in Solution: An Integrated NMR and SAXS Study.

Xi Zhaoyong Z Whitley Matthew J MJ Gronenborn Angela M AM

Structure (London, England : 1993) 20170223 3

βγ-Crystallins are long-lived eye lens proteins that are crucial for lens transparency and refractive power. Each βγ-crystallin comprises two homologous domains, which are connected by a short linker. γ-Crystallins are monomeric, while β-crystallins crystallize as dimers and multimers. In the crystal, human βB2-crystallin is a domain-swapped dimer while the N-terminally truncated βB1-crystallin forms a face-en-face dimer. Combining and integrating data from multi-angle light scattering, nuclear ...[more]

PMID: 28238532

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Project description:Atomic-level structural information on alphaB-Crystallin (alphaB), a prominent member of the small heat-shock protein family, has been a challenge to obtain due its polydisperse oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on an approximately 580-kDa human alphaB assembled from 175-residue 20-kDa subunits. An approximately 100-residue alpha-crystallin domain is common to all small heat-shock proteins, and solution-state NMR was performed on two different alpha-crystallin domain constructs isolated from alphaB. In vitro, the chaperone-like activities of full-length alphaB and the isolated alpha-crystallin domain are identical. Chemical shifts of the backbone and C(beta) resonances have been obtained for residues 64-162 (alpha-crystallin domain plus part of the C-terminus) in alphaB and the isolated alpha-crystallin domain by solid-state and solution-state NMR, respectively. Both sets of data strongly predict six beta-strands in the alpha-crystallin domain. A majority of residues in the alpha-crystallin domain have similar chemical shifts in both solid-state and solution-state, indicating similar structures for the domain in its isolated and oligomeric forms. Sites of intersubunit interaction are identified from chemical shift differences that cluster to specific regions of the alpha-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within alphaB. Evidence for a novel dimerization motif in the human alpha-crystallin domain is obtained by a comparison of (i) solid-state and solution-state chemical shift data and (ii) (1)H-(15)N heteronuclear single quantum coherence spectra as a function of pH. The isolated alpha-crystallin domain undergoes a dimer-monomer transition over the pH range 7.5-6.8. This steep pH-dependent switch may be important for alphaB to function optimally (e.g., to preserve the filament integrity of cardiac muscle proteins such as actin and desmin during cardiac ischemia, which is accompanied by acidosis).

Dataset Information

Human ?B2-Crystallin Forms a Face-en-Face Dimer in Solution: An Integrated NMR and SAXS Study.

Publications

Human βB2-Crystallin Forms a Face-en-Face Dimer in Solution: An Integrated NMR and SAXS Study.

Similar Datasets

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