Towards a Molecular Understanding of Phase Separation in the Lens: a Comparison of the X-ray Structures of Two HighTcγ-Crystallins, γE and γF, with Two LowTcγ-Crystallins, γB and γD

Norledge, B.V.; Hay, Regine E.; Bateman, O.A.; Slingsby, C.; Driessen, H.P.C.

doi:10.1006/exer.1997.0368

Cited by 44 publications

(50 citation statements)

References 37 publications

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“…Extensive biophysical studies have been performed in vitro on members of the bg-crystallin superfamily [99][100][101][102][103]. The g-crystallins exhibit attractive forces between molecules [104] and form micelles under appropriate conditions [13].…”

Section: Structure and Function Of The Lens Crystallinsmentioning

confidence: 99%

Cataract as a Protein‐Aggregation Disease

Wang

King

2010

Protein Misfolding Diseases

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Section: Structure and Function Of The Lens Crystallinsmentioning

confidence: 99%

Cataract as a Protein‐Aggregation Disease

Wang

King

2010

Protein Misfolding Diseases

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“…The β and γ crystallins are members of the βγ gene superfamily of crystallins, which all possess a Greek-key fold protein motif, but whose non-refractive functions remain undetermined (Liaw et al, 1992;Slingsby and Clout, 1999;Wistow, 1993). Depending on the species, between four and six of the known β and γ crystallin genes are expressed (Chiou et al, 1986;Norledge et al, 1997).…”

mentioning

confidence: 99%

“…When the cow lens is cooled from the body temperature of 37°C to about 19°C, it begins to develop an opacity, a phenomenon known as cold-cataract, which has been attributed to the cold instability of some of the constituent γ crystallins, resulting in a liquid-liquid phase transition within the lens (Delaye et al, 1982;Gulik-Krzywicki et al, 1984;Norledge et al, 1997;Siezen et al, 1985). Cold-cataract has also been reported in a few other endothermic mammals such as the rat Lerman, 1964, 1965).…”

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Cold-stable eye lens crystallins of the Antarctic nototheniid toothfishDissostichus mawsoniNorman

Kiss

Mirarefi

Ramakrishnan

et al. 2004

Journal of Experimental Biology

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SUMMARY The eye lenses of the Antarctic nototheniid fishes that inhabit the perennially freezing Antarctic seawater are transparent at –2°C,whereas the cold-sensitive mammalian and tropical fish lenses display cold-induced cataract at 20°C and 7°C, respectively. No cold-cataract occurs in the giant Antarctic toothfish Dissostichus mawsoni lens when cooled to temperatures as low as –12°C, indicating highly cold-stable lens proteins. To investigate this cold stability, we characterised the lens crystallin proteins of the Antarctic toothfish, in parallel with those of the sub-tropical bigeye tuna Thunnus obesusand the endothermic cow Bos taurus, representing three disparate thermal climes (–2°C, 18°C and 37°C, respectively). Sizing chromatography resolved their lens crystallins into three groups,α/βH, β and γ, with γ crystallins being the most abundant (>40%) lens proteins in fish, in contrast to the cow lens where they comprise only 19%. The upper thermal stability of these crystallin components correlated with the body temperature of the species. In vitro chaperone assays showed that fish α crystallin can protect same-species γ crystallins from heat denaturation, as well as lysozyme from DTT-induced unfolding, and therefore are small Heat Shock Proteins (sHSP)like their mammalian counterparts. Dynamic light scattering measured an increase in size of αγ crystallin mixtures upon heating, which supports formation of the αγ complex as an integral part of the chaperone process. Surprisingly, in cross-species chaperone assays, tunaα crystallins only partly protected toothfish γ crystallins, while cow α crystallins completely failed to protect, indicating partial and no αγ interaction, respectively. Toothfish γ was likely to be the component that failed to interact, as the supernatant from a cowα plus toothfish γ incubation could chaperone cow γcrystallins in a subsequent heat incubation, indicating the presence of uncomplexed cow α. This suggests that the inability of toothfish γcrystallins to fully complex with tuna α, and not at all with the cowα crystallins, may have its basis in adaptive changes in the protein that relate to the extreme cold-stability of the toothfish lens.

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“…The X-ray structures of one member of the P-family (PB2: Bax et al, 1990) and four members of the y-crystallins (yB : Blundell et al, 1981;yD: Chirgadze et al, 1996; yE and yF: (Norledge et al, 1997) have been solved. These studies revealed a common two-domain architecture with each polypeptide folded into two similar P-sheet domains that are further divided into two Greek key motifs.…”

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X‐ray structures of three interface mutants of γB‐crystallin from bovine eye lens

1998

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AbstractyB-crystallin consists of two domains each comprising two "Greek key" motifs. Both domains fold independently, and domain interactions contribute significantly to the stability of the C-terminal domain. In a previous study (Palme S et al., 1996, Protein Sci 6:1529-1636 it was shown that Phe56 from the N-terminal domain, a residue involved in forming a hydrophobic core at the domain interface, effects the interaction of the two domains, and therefore, the stability of the C-terminal domain. Ala or Asp at position 56 drastically decreased the stability of the C-terminal domain, whereas Trp had a more moderate effect. In this article we present the X-ray structures of these interface mutants and correlate them with the stability data. The mutations do not effect the overall structure of the molecule. No structural changes are observed in the vicinity of the replaced residue, suggesting that the local structure is too rigid to allow compensations for the amino acid replacements. In the mutants yB-F56A and -F56D, a solvent-filled groove accessible to the bulk solvent is created by the replacement of the bulky Phe side chain. In yB-F56W, the pyrrole moiety of the indole ring replaces the phenyl side chain of the wild type. With the exception of yB-F56W, there is a good correlation between the hydrophobicity of the amino acid at position 56 according to the octanol scale and the stability of the C-terminal domain. In yB-F56W, the C-terminal domain is less stable than estimated from the hydrophobicity, presumably because the ring nitrogen (Nel) has no partner to form hydrogen bonds. The data suggest that the packing of hydrophobic residues in the interface core is important for domain interactions and the stability of yB-crystallin. Apparently, for protein stability, the same principles apply for hydrophobic cores within domains and at domain interfaces.

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Towards a Molecular Understanding of Phase Separation in the Lens: a Comparison of the X-ray Structures of Two HighTcγ-Crystallins, γE and γF, with Two LowTcγ-Crystallins, γB and γD

Cited by 44 publications

References 37 publications

Cataract as a Protein‐Aggregation Disease

Cataract as a Protein‐Aggregation Disease

Cold-stable eye lens crystallins of the Antarctic nototheniid toothfishDissostichus mawsoniNorman

X‐ray structures of three interface mutants of γB‐crystallin from bovine eye lens

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