Specific Glutamine and Asparagine Residues of γ-S Crystallin Are Resistant to in Vivo Deamidation

Takemoto, L.; Boyle, Daniel

doi:10.1074/jbc.m002809200

Cited by 18 publications

(18 citation statements)

References 10 publications

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“…15,23 One rationale of this study was to resolve a conflict in the literature regarding deamidation of Gln92. Two studies suggested that there was no deamidation of this residue 11,12 ; however, we obtained clear mass spectral evidence that there is significant deamidation at this site (Fig. 1).…”

Section: Discussionmentioning

confidence: 72%

“…A probable reason for the difference in the two datasets is that the earlier studies that found no deamidation were based solely on HPLC elution times in the absence of mass spectral data. 11,12 Apparently, this method is subject to interference by coeluting species and is not sufficiently sensitive to detect deamidation. There are a total of nine Gln residues in cS crystallin, yet few 13 appear to undergo significant deamidation.…”

Section: Discussionmentioning

confidence: 99%

“…Unfortunately, there is controversy in the literature concerning the sites and extent of deamidation in cS crystallin. With regard to Gln92, a residue located in the crucial linker region between the two domains, some authors have reported no deamidation, 11,12 whereas others have found significant deamidation 13,14 in older lenses.…”

Section: Introductionmentioning

confidence: 99%

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Age‐dependent deamidation of glutamine residues in human γS crystallin: Deamidation and unstructured regions

2012

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Human aging is associated with the deterioration of long-lived proteins. Gradual cumulative modifications to the life-long proteins of the lens may ultimately be responsible for the pronounced alterations to the optical and physical properties that characterize lenses from older people. cS crystallin, a major human lens protein, is known to undergo several age-dependent changes. Using proteomic techniques, a site of deamidation involving glutamine 92 has been characterized and its time course established. The proportion of deamidation increased from birth to teen-age years and then plateaud. Deamidation at this site increased again in the eighth decade of life. There was no significant difference in the extent of deamidation between cataract and age-matched normal lenses. Gln92 is located in the linker region between the two domains, and the introduction of a negative charge at this site may alter the interaction between the two regions of the protein. Gln170, which is located in another unstructured part of cS crystallin, showed a similar deamidation profile to that of Gln92. As the other Gln residues in b-sheet regions of cS crystallin appear to remain as amides, modification of Gln92 and Gln170 thus conforms to a pattern whereby deamidation is localized to the unstructured regions of long-lived proteins.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

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Age‐dependent deamidation of glutamine residues in human γS crystallin: Deamidation and unstructured regions

2012

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“…Gln deamidations over periods of many years in vivo in slow-turnover proteins of long-lived organisms such as human eye lens proteins (22) can be of substantial biological significance. Gln-Gly sequences in sterically unhindered locations of proteins that lack shorter-lived Asn residues also affect the deamidation index.…”

Section: Resultsmentioning

confidence: 99%

Protein deamidation

Robinson

2002

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

258

219

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A completely automatic computerized technique for the quantitative estimation of the deamidation rates of any protein for which the three-dimensional structure is known has been developed. Calculations of the specific deamidation rates of 170,014 asparaginyl residues in 13,335 proteins have been carried out. The calculated values have good quantitative reliability when compared with experimental measurements. These rates demonstrate that deamidation may be a biologically relevant phenomenon in a remarkably large percentage of proteins.asparaginyl residue deamidation ͉ coefficient of deamidation ͉ deamidation index C hanges in peptide and protein structure through the spontaneous nonenzymatic deamidation of glutaminyl and asparaginyl residues have been observed in many in vitro and in vivo experiments. Rates of deamidation of individual amide residues depend upon primary sequence, three-dimensional (3D) structure, and solution properties such as pH, temperature, ionic strength, and buffer ions (1-8).Deamidation at neutral pH introduces a negative charge at the deamidation site and sometimes also leads to ␤ isomerization. These alterations in structure affect the properties of peptides and proteins in chemically and biologically important ways. It has been suggested that in vivo deamidation of proteins serves as a molecular timer of biological events and as a mechanism for postsynthetic production of unique proteins of biological significance (2,4,6,7,9,10). In the case of in vivo protein turnover, the use of deamidation as a molecular timer has been experimentally demonstrated (11-13).Progress in the understanding of deamidation and its potential biological importance has been impeded by the lack of reliable and useful experimental and theoretical information about the deamidation of most proteins. Experimental studies of the deamidation of individual proteins are laborious and time consuming. Until recently, there were no other means by which to estimate the deamidation rates of specific amides.The deamidation rates of individual Asn residues in a protein can now be reliably predicted as a result of two recent advances. First, the sequence-controlled Asn deamidation rates of most of the 400 possible near-neighbor combinations in pentapeptide models have been measured (10); the deamidation rates of a representative group of Gln pentapeptides have been determined (N.E.R. & A. B. Robinson, unpublished work); and the relevance of these rate libraries has been established (14). Second, these rates and the 3D structures of proteins with well characterized deamidations have been combined to produce a computation method that correctly predicts the deamidation rates of most Asn residues for which the 3D structure is known (15). This method has been shown to be Ϸ95% reliable in predicting relative deamidation rates of Asn residues within a single protein, and it is also useful for the prediction of absolute deamidation rates. It has been used to estimate the deamidation rates of 1,371 asparaginyl residues in 126 human pro...

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“…It has been shown that the tryptic peptide containing Asp 138(143) is deamidated when isolated from human cataractous lens proteins (44), whereas when the corresponding peptide is isolated from the fetal-embryonic region of aged transparent human lenses, it is not deamidated (46). Asp 138(143) is in the region of the domain dimer interface but has a moderate solvent exposure (Fig.…”

Section: Discussionmentioning

confidence: 99%

The X-ray Crystal Structure of Human γS-crystallin C-terminal Domain

Purkiss¹,

Bateman²,

Goodfellow³

et al. 2002

Journal of Biological Chemistry

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␥S-crystallin is a major human lens protein found in the outer region of the eye lens, where the refractive index is low. Because crystallins are not renewed they acquire post-translational modifications that may perturb stability and solubility. In common with other members of the ␤␥-crystallin superfamily, ␥S-crystallin comprises two similar ␤-sheet domains. The crystal structure of the C-terminal domain of human ␥S-crystallin has been solved at 2.4 Å resolution. The structure shows that in the in vitro expressed protein, the buried cysteines remain reduced. The backbone conformation of the "tyrosine corner" differs from that of other ␤␥-crystallins because of deviation from the consensus sequence. The two C-terminal domains in the asymmetric unit are organized about a slightly distorted 2-fold axis to form a dimer with similar geometry to full-length two-domain family members. Two glutamines found in lattice contacts may be important for short range interactions in the lens. An asparagine known to be deamidated in human cataract is located in a highly ordered structural region.

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Specific Glutamine and Asparagine Residues of γ-S Crystallin Are Resistant to in Vivo Deamidation

Cited by 18 publications

References 10 publications

Age‐dependent deamidation of glutamine residues in human γS crystallin: Deamidation and unstructured regions

Age‐dependent deamidation of glutamine residues in human γS crystallin: Deamidation and unstructured regions

Protein deamidation

The X-ray Crystal Structure of Human γS-crystallin C-terminal Domain

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