NMR Studies of Eye Lens Crystallins

Martin, Rachel W.

doi:10.1002/9780470034590.emrstm1354

Cited by 4 publications

(3 citation statements)

References 124 publications

(108 reference statements)

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“…Therefore, many structural studies have been performed using solution‐state NMR, as reviewed in ref. [45] and discussed for several cataract‐related variants in Section 5. In addition to providing ensembles of structures in solution, this method enables the investigation of dynamics over a wide range of timescales and to detect rare conformational states [46–48] .…”

Section: Biophysical Techniques For Studying Crystallinsmentioning

confidence: 99%

Chemical Properties Determine Solubility and Stability in βγ‐Crystallins of the Eye Lens

et al. 2021

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βγ-Crystallins are the primary structural and refractive proteins found in the vertebrate eye lens. Because crystallins are not replaced after early eye development, their solubility and stability must be maintained for a lifetime, which is even more remarkable given the high protein concentration in the lens. Aggregation of crystallins caused by mutations or post-translational modifications can reduce crystallin protein stability and alter intermolecular interactions. Common post-translational modifications that can cause age-related cataracts include deamidation, oxidation, and tryptophan derivatization. Metal ion binding can also trigger reduced crystallin solubility through a variety of mechanisms. Interprotein interactions are critical to maintaining lens transparency: crystallins can undergo domain swapping, disulfide bonding, and liquid-liquid phase separation, all of which can cause opacity depending on the context. Important experimental techniques for assessing crystallin conformation in the absence of a high-resolution structure include dye-binding assays, circular dichroism, fluorescence, light scattering, and transition metal FRET.

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Section: Biophysical Techniques For Studying Crystallinsmentioning

confidence: 99%

Chemical Properties Determine Solubility and Stability in βγ‐Crystallins of the Eye Lens

et al. 2021

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“…Solving the structures of α-crystallins in biologically relevant complexes is a challenging endeavor. Their dynamic and polydisperse nature makes them particularly suitable for NMR (see the sidebar titled NMR Assignments and Structure Determination) (53,54), and in many cases…”

Section: Solution Nmrmentioning

confidence: 99%

α-Crystallins in the Vertebrate Eye Lens: Complex Oligomers and Molecular Chaperones

Sprague-Piercy

Rocha

Kwok

et al. 2021

Annu. Rev. Phys. Chem.

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α-Crystallins are small heat-shock proteins that act as holdase chaperones. In humans, αA-crystallin is expressed only in the eye lens, while αB-crystallin is found in many tissues. α-Crystallins have a central domain flanked by flexible extensions and form dynamic, heterogeneous oligomers. Structural models show that both the C- and N-terminal extensions are important for controlling oligomerization through domain swapping. α-Crystallin prevents aggregation of damaged β- and γ-crystallins by binding to the client protein using a variety of binding modes. α-Crystallin chaperone activity can be compromised by mutation or posttranslational modifications, leading to protein aggregation and cataract. Because of their high solubility and their ability to form large, functional oligomers, α-crystallins are particularly amenable to structure determination by solid-state NMR and solution NMR, as well as cryo-electron microscopy. Expected final online publication date for the Annual Review of Physical Chemistry, Volume 72 is April 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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“…Point mutations are frequently assumed to have only a very local effect on protein structure; our work and that of other groups have indicated that this is often not the case for crystallins. 35 As discussed in the previous section, the relatively minor conformational change caused by the G18V mutation nevertheless propagates down the polypeptide chain through more than half of the N-terminal domain. 30 In collaboration (A) Thermal unfolding data for variants of human γS-crystallin: γS-WT (green), γS-G18V (light blue), γS-G106V (magenta), and γS-G106V/M108R (purple).…”

Section: Clients By the Holdase Chaperone αB-crystallinmentioning

confidence: 87%

Function and Aggregation in Structural Eye Lens Crystallins

et al. 2020

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Conspectus Crystallins are transparent, refractive proteins that contribute to the focusing power of the vertebrate eye lens. These proteins are extremely soluble and resist aggregation for decades, even under crowded conditions. Crystallins have evolved to avoid strong interprotein interactions and have unusual hydration properties. Crystallin aggregation resulting from mutation, damage, or aging can lead to cataract, a disease state characterized by opacity of the lens. Different aggregation mechanisms can occur, following multiple pathways and leading to aggregates with varied morphologies. Studies of variant proteins found in individuals with childhood-onset cataract have provided insight into the molecular factors underlying crystallin stability and solubility. Modulation of exposed hydrophobic surface is critical, as is preventing specific intermolecular interactions that could provide nucleation sites for aggregation. Biophysical measurements and structural biology techniques are beginning to provide a detailed picture of how crystallins crowd into the lens, providing high refractivity while avoiding excessively tight binding that would lead to aggregation. Despite the central biological importance of refractivity, relatively few experimental measurements have been made for lens crystallins. Our work and that of others have shown that hydration is important to the high refractive index of crystallin proteins, as are interactions between pairs of aromatic residues and potentially other specific structural features. This Account describes our efforts to understand both the functional and disease states of vertebrate eye lens crystallins, particularly the γ-crystallins. We use a variety of biophysical techniques, notably NMR spectroscopy, to investigate crystallin stability and solubility. In the first section, we describe efforts to understand the relative stability and aggregation propensity of different γS-crystallin variants. The second section focuses on interactions of these proteins with the holdase chaperone αB-crystallin. The third, fourth, and fifth sections explore different modes of aggregation available to crystallin proteins, and the final section highlights the importance of refractive index and the sometimes conflicting demands of selection for refractivity and solubility.

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NMR Studies of Eye Lens Crystallins

Cited by 4 publications

References 124 publications

Chemical Properties Determine Solubility and Stability in βγ‐Crystallins of the Eye Lens

Chemical Properties Determine Solubility and Stability in βγ‐Crystallins of the Eye Lens

α-Crystallins in the Vertebrate Eye Lens: Complex Oligomers and Molecular Chaperones

Function and Aggregation in Structural Eye Lens Crystallins

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