Colloidal Characterization and Thermodynamic Stability of Binary Eye Lens Protein Mixtures

Dorsaz, Nicolas; Thurston, George M.; Stradner, Anna; Schurtenberger, Peter; Foffi, Giuseppe

doi:10.1021/jp807103f

Cited by 30 publications

(83 citation statements)

References 83 publications

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“…Thus these data provide direct experimental evidence for the prediction of Dorsaz et al (22) that an increase in the attractive interactions between the α-and γ-crystallins will make mixtures of these proteins unstable, tending toward density-driven phase separation, and can thereby contribute to cataract formation. This work also constitutes a prime example of a cataract-associated mutation that highlights the importance of heterologous proteinprotein interactions optimized to maintain transparency and how changes in these interactions can lead to instability and opacity of the human lens.…”

supporting

confidence: 67%

“…Here we show that all the mixtures containing E107A and α-crystallin (E107A-α) consistently show higher lightscattering intensities relative to mixtures of HGD and α-crystallin (HGD-α) of identical composition. Furthermore, as the weight fraction of α-crystallin (X α ) in E107A-α mixtures is raised incrementally from 0.2 to 0.5 (a value comparable to that in the lens nucleus) (24), the observed changes in the phase separation temperature (T ph ) and the tie lines of the mixtures are consistent with an increase in the attraction between E107A and α-crystallin (22).…”

mentioning

confidence: 78%

“…Because the net γ-γ interactions are essentially unaltered in E107A relative to HGD, the increase in pI raises the possibility of altered electrostatic interactions between E107A and other crystallins-for example, one with a lower pI. A likely candidate is α-crystallin, because it is negatively charged at physiological pH (17), and it is already known that interactions among α-and γ-crystallins are fine tuned for optimal packing and transparency, and small changes in such interactions lead to instability (18)(19)(20)(21)(22).We therefore examined mixtures containing solutions of α-crystallin and either HGD or E107A, at compositions representing those in the young human lens and approaching those in the lens nucleus (23). Here we show that all the mixtures containing E107A and α-crystallin (E107A-α) consistently show higher lightscattering intensities relative to mixtures of HGD and α-crystallin (HGD-α) of identical composition.…”

mentioning

confidence: 99%

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confidence: 99%

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Cataract-associated mutant E107A of human γD-crystallin shows increased attraction to α-crystallin and enhanced light scattering

Banerjee¹,

Pande²,

Patrosz

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Several point mutations in human γD-crystallin (HGD) are now known to be associated with cataract. So far, the in vitro studies of individual mutants of HGD alone have been sufficient in providing plausible molecular mechanisms for the associated cataract in vivo. Nearly all the mutant proteins in solution showed compromised solubility and enhanced light scattering due to altered homologous γ-γ crystallin interactions. In sharp contrast, here we present an intriguing case of a human nuclear cataract-associated mutant of HGD-namely Glu107 to Ala (E107A), which is nearly identical to the wild type in structure, stability, and solubility properties, with one exception: Its pI is higher by nearly one pH unit. This increase dramatically alters its interaction with α-crystallin. There is a striking difference in the liquid-liquid phase separation behavior of E107A-α-crystallin mixtures compared to HGD-α-crystallin mixtures, and the light-scattering intensities are significantly higher for the former. The data show that the two coexisting phases in the E107A-α mixtures differ much more in protein density than those that occur in HGD-α mixtures, as the proportion of α-crystallin approaches that in the lens nucleus. Thus in HGD-α mixtures, the demixing of phases occurs primarily by protein type while in E107A-α mixtures it is increasingly governed by protein density. Analysis of these results suggests that the cataract due to the E107A mutation could result from the instability caused by the altered attractive interactions between dissimilar proteins -i.e., heterologous γ-α crystallin interactions-primarily due to the change in surface electrostatic potential in the mutant protein.T he vertebrate lens contains three families of constituent proteins, the α-, β-, and γ-crystallins, closely packed such that the total protein concentration in the central region of the lens, i.e., nucleus, exceeds 400 mg∕mL (1). Normally, the close protein packing ensures that short-range order is maintained within the fiber cell, such that fluctuations in the refractive index that cause light scattering are minimized, and the lens is transparent (2, 3). Disruption of short-range order associated with aging, altered environment, or mutations in crystallins can cause increased light scattering and cataract.Cataract-associated mutations in the crystallin genes are known to occur in all three crystallin families (1, 4) and show a variety of phenotypes. Over the last decade, we have focused on the point mutations occurring in human γD-crystallin (HGD), a member of the γ-crystallin family expressed at high levels along with γC-and γS-crystallins in the human lens (5). By comparing the properties of several mutants of HGD in solution with those of the wild type, we have identified specific changes in the homologous (i.e., γ-γ interactions) that led to the formation of distinct condensed phases (6, 7) and accounted for the increased light scattering due to these mutations (8-13). These studies revealed a class of γ-crystallin mutations in which smal...

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supporting

confidence: 67%

mentioning

confidence: 78%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Cataract-associated mutant E107A of human γD-crystallin shows increased attraction to α-crystallin and enhanced light scattering

Banerjee¹,

Pande²,

Patrosz

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…55,56 It is therefore widely used to calculate the phase diagram of protein solutions. [57][58][59][60][61] Within TPT, the free energy, F, is expanded in powers of the perturbation potential u p = u − u 0 , where u 0 is the pair potential of a reference system and u the total proteinprotein pair potential (see Eq. (4)).…”

Section: Phase Behavior and Free Energy By Thermodynamic Perturbationmentioning

confidence: 99%

Effect of glycerol and dimethyl sulfoxide on the phase behavior of lysozyme: Theory and experiments

Gögelein

Wagner

Cardinaux

et al. 2012

The Journal of Chemical Physics

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Salt, glycerol, and dimethyl sulfoxide (DMSO) are used to modify the properties of protein solutions. We experimentally determined the effect of these additives on the phase behavior of lysozyme solutions. Upon the addition of glycerol and DMSO, the fluid-solid transition and the gas-liquid coexistence curve (binodal) shift to lower temperatures and the gap between them increases. The experimentally observed trends are consistent with our theoretical predictions based on the thermodynamic perturbation theory and the Derjaguin-Landau-Verwey-Overbeek model for the lysozyme-lysozyme pair interactions. The values of the parameters describing the interactions, namely the refractive indices, dielectric constants, Hamaker constant and cut-off length, are extracted from literature or are experimentally determined by independent experiments, including static light scattering, to determine the second virial coefficient. We observe that both, glycerol and DMSO, render the potential more repulsive, while sodium chloride reduces the repulsion.

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RETRACTED ARTICLE: Attractive interactions prevail in dilute solutions of human recombinant α-crystallins

Georgalis

Peschek

Appavou³

2013

Eur Biophys J

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Colloidal Characterization and Thermodynamic Stability of Binary Eye Lens Protein Mixtures

Cited by 30 publications

References 83 publications

Cataract-associated mutant E107A of human γD-crystallin shows increased attraction to α-crystallin and enhanced light scattering

Cataract-associated mutant E107A of human γD-crystallin shows increased attraction to α-crystallin and enhanced light scattering

Effect of glycerol and dimethyl sulfoxide on the phase behavior of lysozyme: Theory and experiments

RETRACTED ARTICLE: Attractive interactions prevail in dilute solutions of human recombinant α-crystallins

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