Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins

Kirsten Lampi, Yung H. Kim, Hans Peter Bächinger, Bruce A. Boswell, Robyn A. Lindner, John A. Carver, Thomas (Tom) Shearer, Larry David, Deborah M. Kapfer

Research output: Contribution to journalArticle

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Abstract

Purpose: To determine how deamidation and partial loss of the N- and C-terminal extensions alter the heat stability of βB1-crystallin. Methods: Human lens βB1, a deamidated βB1, Q204E, and αA-crystallins were expressed. Truncated βB1 was generated by proteolytic removal of part of its terminal extensions. The aggregation and precipitation of these proteins due to heating was monitored by circular dichroism and light scattering. The effect of heat on the stability of both monomers and oligomers was investigated. The flexibility of the extensions in wild type and deamidated βB1 was assessed by 1H NMR spectroscopy. Results: With heat, deamidated βB1 precipitated more readily than wild type βB1. Similar effects were obtained for either monomers or oligomers. Flexibility of the N-terminal extension in deamidated βB1 was significantly reduced compared to the wild type protein. Truncation of the extensions further increased the rate of heat-induced precipitation of deamidated βB1. The presence of the molecular chaperone, αA-crystallin, prevented precipitation of modified βB1s. More αA was needed to chaperone the truncated and deamidated βB1 than deamidated βB1 or truncated βB1. Conclusions: Deamidation and truncation of βB1 led to destabilization of the protein and decreased stability to heat. Decreased stability of lens crystallins may contribute to their insolubilization and cataract formation.

Original languageEnglish (US)
Pages (from-to)359-366
Number of pages8
JournalMolecular Vision
Volume8
StatePublished - 2002

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Crystallins
Hot Temperature
Lenses
Molecular Chaperones
Protein Stability
Circular Dichroism
Heating
Cataract
Proteins
Magnetic Resonance Spectroscopy
Light

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Lampi, K., Kim, Y. H., Bächinger, H. P., Boswell, B. A., Lindner, R. A., Carver, J. A., ... Kapfer, D. M. (2002). Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins. Molecular Vision, 8, 359-366.

Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins. / Lampi, Kirsten; Kim, Yung H.; Bächinger, Hans Peter; Boswell, Bruce A.; Lindner, Robyn A.; Carver, John A.; Shearer, Thomas (Tom); David, Larry; Kapfer, Deborah M.

In: Molecular Vision, Vol. 8, 2002, p. 359-366.

Research output: Contribution to journalArticle

Lampi, K, Kim, YH, Bächinger, HP, Boswell, BA, Lindner, RA, Carver, JA, Shearer, TT, David, L & Kapfer, DM 2002, 'Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins', Molecular Vision, vol. 8, pp. 359-366.
Lampi K, Kim YH, Bächinger HP, Boswell BA, Lindner RA, Carver JA et al. Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins. Molecular Vision. 2002;8:359-366.
Lampi, Kirsten ; Kim, Yung H. ; Bächinger, Hans Peter ; Boswell, Bruce A. ; Lindner, Robyn A. ; Carver, John A. ; Shearer, Thomas (Tom) ; David, Larry ; Kapfer, Deborah M. / Decreased heat stability and increased chaperone requirement of modified human βB1-crystallins. In: Molecular Vision. 2002 ; Vol. 8. pp. 359-366.
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abstract = "Purpose: To determine how deamidation and partial loss of the N- and C-terminal extensions alter the heat stability of βB1-crystallin. Methods: Human lens βB1, a deamidated βB1, Q204E, and αA-crystallins were expressed. Truncated βB1 was generated by proteolytic removal of part of its terminal extensions. The aggregation and precipitation of these proteins due to heating was monitored by circular dichroism and light scattering. The effect of heat on the stability of both monomers and oligomers was investigated. The flexibility of the extensions in wild type and deamidated βB1 was assessed by 1H NMR spectroscopy. Results: With heat, deamidated βB1 precipitated more readily than wild type βB1. Similar effects were obtained for either monomers or oligomers. Flexibility of the N-terminal extension in deamidated βB1 was significantly reduced compared to the wild type protein. Truncation of the extensions further increased the rate of heat-induced precipitation of deamidated βB1. The presence of the molecular chaperone, αA-crystallin, prevented precipitation of modified βB1s. More αA was needed to chaperone the truncated and deamidated βB1 than deamidated βB1 or truncated βB1. Conclusions: Deamidation and truncation of βB1 led to destabilization of the protein and decreased stability to heat. Decreased stability of lens crystallins may contribute to their insolubilization and cataract formation.",
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AU - Lampi, Kirsten

AU - Kim, Yung H.

AU - Bächinger, Hans Peter

AU - Boswell, Bruce A.

AU - Lindner, Robyn A.

AU - Carver, John A.

AU - Shearer, Thomas (Tom)

AU - David, Larry

AU - Kapfer, Deborah M.

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N2 - Purpose: To determine how deamidation and partial loss of the N- and C-terminal extensions alter the heat stability of βB1-crystallin. Methods: Human lens βB1, a deamidated βB1, Q204E, and αA-crystallins were expressed. Truncated βB1 was generated by proteolytic removal of part of its terminal extensions. The aggregation and precipitation of these proteins due to heating was monitored by circular dichroism and light scattering. The effect of heat on the stability of both monomers and oligomers was investigated. The flexibility of the extensions in wild type and deamidated βB1 was assessed by 1H NMR spectroscopy. Results: With heat, deamidated βB1 precipitated more readily than wild type βB1. Similar effects were obtained for either monomers or oligomers. Flexibility of the N-terminal extension in deamidated βB1 was significantly reduced compared to the wild type protein. Truncation of the extensions further increased the rate of heat-induced precipitation of deamidated βB1. The presence of the molecular chaperone, αA-crystallin, prevented precipitation of modified βB1s. More αA was needed to chaperone the truncated and deamidated βB1 than deamidated βB1 or truncated βB1. Conclusions: Deamidation and truncation of βB1 led to destabilization of the protein and decreased stability to heat. Decreased stability of lens crystallins may contribute to their insolubilization and cataract formation.

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