Mutation-Induced Deamidation of Corneal Dystrophy-Related Transforming Growth Factor β-Induced Protein

TY - JOUR

T1 - Mutation-Induced Deamidation of Corneal Dystrophy-Related Transforming Growth Factor β-Induced Protein

AU - Nielsen, Nadia Sukusu

AU - Juhl, Dennis Wilkens

AU - Poulsen, Ebbe Toftgaard

AU - Lukassen, Marie V

AU - Poulsen, Emil Christian

AU - Risør, Michael W

AU - Scavenius, Carsten

AU - Enghild, Jan Johannes

PY - 2017/12/12

Y1 - 2017/12/12

N2 - Mutations in the transforming growth factor β-induced protein (TGFBIp) cause phenotypically diverse corneal dystrophies, where protein aggregation in the cornea leads to severe visual impairment. Previous studies have shown a relationship between mutant-specific corneal dystrophy phenotypes and the thermodynamic stability of TGFBIp. Using liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance (NMR), we investigated correlations between the structural integrity of disease-related mutants of the fourth FAS1 domain (FAS1-4) and deamidation of TGFBIp residue Asn622. We observed a high rate of Asn622 deamidation in the A546D and A546D/P551Q FAS1-4 mutants that were both largely unstructured as determined by NMR. Conversely, the more structurally organized A546T and V624M FAS1-4 mutants had reduced deamidation rates, suggesting that a folded and stable FAS1-4 domain precludes Asn622 deamidation. Wild-type, R555Q, and R555W FAS1-4 mutants displayed very slow deamidation, which agrees with their similar and ordered NMR structures, where Asn622 is in a locked conformation. We confirmed the FAS1-4 mutational effect on deamidation rates in full-length TGFBIp mutants and found a similar ranking compared to that of the FAS1-4 domain alone. Consequently, the deamidation rate of Asn622 can be used to predict the structural effect of the many destabilizing and/or stabilizing mutations reported for TGFBIp. In addition, the deamidation of Asn622 may influence the pathophysiology of TGFBIp-induced corneal dystrophies.

AB - Mutations in the transforming growth factor β-induced protein (TGFBIp) cause phenotypically diverse corneal dystrophies, where protein aggregation in the cornea leads to severe visual impairment. Previous studies have shown a relationship between mutant-specific corneal dystrophy phenotypes and the thermodynamic stability of TGFBIp. Using liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance (NMR), we investigated correlations between the structural integrity of disease-related mutants of the fourth FAS1 domain (FAS1-4) and deamidation of TGFBIp residue Asn622. We observed a high rate of Asn622 deamidation in the A546D and A546D/P551Q FAS1-4 mutants that were both largely unstructured as determined by NMR. Conversely, the more structurally organized A546T and V624M FAS1-4 mutants had reduced deamidation rates, suggesting that a folded and stable FAS1-4 domain precludes Asn622 deamidation. Wild-type, R555Q, and R555W FAS1-4 mutants displayed very slow deamidation, which agrees with their similar and ordered NMR structures, where Asn622 is in a locked conformation. We confirmed the FAS1-4 mutational effect on deamidation rates in full-length TGFBIp mutants and found a similar ranking compared to that of the FAS1-4 domain alone. Consequently, the deamidation rate of Asn622 can be used to predict the structural effect of the many destabilizing and/or stabilizing mutations reported for TGFBIp. In addition, the deamidation of Asn622 may influence the pathophysiology of TGFBIp-induced corneal dystrophies.

KW - Journal Article

UR - http://www.scopus.com/inward/record.url?scp=85038209870&partnerID=8YFLogxK

U2 - 10.1021/acs.biochem.7b00668

DO - 10.1021/acs.biochem.7b00668

M3 - Journal article

C2 - 29140698

SN - 0006-2960

VL - 56

SP - 6470

EP - 6480

JO - Biochemistry

JF - Biochemistry

IS - 49

ER -