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Two stable unfolding intermediates of the disease-causing L68Q variant of human cystatin C

Gerhartz, Bernd; Ekiel, I and Abrahamson, Magnus LU (1998) In Biochemistry 37(49). p.17309-17317
Abstract
In hereditary cystatin C amyloid angiopathy (HCCAA), presence of the Leu68 Gln substitution in cystatin C is coupled to a decreased concentration of this major cysteine proteinase inhibitor in cerebrospinal fluid and leads to its amyloid deposition in the brain. We established a high-yield expression system for L68Q cystatin C in Escherichia coli resulting in inclusion body accumulation at a level of 40% of the total cellular protein. Refolding of protein from purified inclusion bodies yielded a pure, almost completely monomeric and active inhibitor. CD and NMR spectroscopy demonstrated that so produced L68Q cystatin C is folded, conformationally homogeneous, and structurally very similar to wild-type cystatin C. Incubation at pH 7.0-5.5... (More)
In hereditary cystatin C amyloid angiopathy (HCCAA), presence of the Leu68 Gln substitution in cystatin C is coupled to a decreased concentration of this major cysteine proteinase inhibitor in cerebrospinal fluid and leads to its amyloid deposition in the brain. We established a high-yield expression system for L68Q cystatin C in Escherichia coli resulting in inclusion body accumulation at a level of 40% of the total cellular protein. Refolding of protein from purified inclusion bodies yielded a pure, almost completely monomeric and active inhibitor. CD and NMR spectroscopy demonstrated that so produced L68Q cystatin C is folded, conformationally homogeneous, and structurally very similar to wild-type cystatin C. Incubation at pH 7.0-5.5 caused the cystatin C variant to dimerize rapidly. The molecular form present at pH 6.0 displayed a slightly increased amount of hydrophobic parts on the surface as measured by 1-anilinonaphthalene-8-sulfonic acid (ANS) binding. NMR results showed that the dimer has a structure similar to that of the wild-type cystatin C dimer formed as a result of slight denaturation. Under more acidic conditions, at pH 4.5, another stable unfolding intermediate of L68Q cystatin C was identified. This molecular form exists in a monomeric state, is characterized by changes in secondary structure according to far UV CD spectroscopy, and shows an altered ANS binding resembling that of a molten globule state. The acidic pH also caused an almost complete monomerization of preformed dimers. The state of denaturation of L68Q cystatin C in vivo is thus a critical factor for the concentration of active cysteine proteinase inhibitor in cerebrospinal fluid and likely also for the development of amyloidosis, in HCCAA patients. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
37
issue
49
pages
17309 - 17317
publisher
The American Chemical Society
external identifiers
  • scopus:0032497910
ISSN
0006-2960
DOI
10.1021/bi980873u
language
English
LU publication?
yes
id
c28a30c8-39ec-4c4a-9530-5ba69be76318 (old id 1113930)
date added to LUP
2008-07-16 14:02:27
date last changed
2017-07-30 03:40:29
@article{c28a30c8-39ec-4c4a-9530-5ba69be76318,
  abstract     = {In hereditary cystatin C amyloid angiopathy (HCCAA), presence of the Leu68 Gln substitution in cystatin C is coupled to a decreased concentration of this major cysteine proteinase inhibitor in cerebrospinal fluid and leads to its amyloid deposition in the brain. We established a high-yield expression system for L68Q cystatin C in Escherichia coli resulting in inclusion body accumulation at a level of 40% of the total cellular protein. Refolding of protein from purified inclusion bodies yielded a pure, almost completely monomeric and active inhibitor. CD and NMR spectroscopy demonstrated that so produced L68Q cystatin C is folded, conformationally homogeneous, and structurally very similar to wild-type cystatin C. Incubation at pH 7.0-5.5 caused the cystatin C variant to dimerize rapidly. The molecular form present at pH 6.0 displayed a slightly increased amount of hydrophobic parts on the surface as measured by 1-anilinonaphthalene-8-sulfonic acid (ANS) binding. NMR results showed that the dimer has a structure similar to that of the wild-type cystatin C dimer formed as a result of slight denaturation. Under more acidic conditions, at pH 4.5, another stable unfolding intermediate of L68Q cystatin C was identified. This molecular form exists in a monomeric state, is characterized by changes in secondary structure according to far UV CD spectroscopy, and shows an altered ANS binding resembling that of a molten globule state. The acidic pH also caused an almost complete monomerization of preformed dimers. The state of denaturation of L68Q cystatin C in vivo is thus a critical factor for the concentration of active cysteine proteinase inhibitor in cerebrospinal fluid and likely also for the development of amyloidosis, in HCCAA patients.},
  author       = {Gerhartz, Bernd and Ekiel, I and Abrahamson, Magnus},
  issn         = {0006-2960},
  language     = {eng},
  number       = {49},
  pages        = {17309--17317},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {Two stable unfolding intermediates of the disease-causing L68Q variant of human cystatin C},
  url          = {http://dx.doi.org/10.1021/bi980873u},
  volume       = {37},
  year         = {1998},
}