Retarded protein folding of deficient human alpha 1-antitrypsin D256V and L41P variants.
alpha(1)-Antitrypsin is the most abundant protease inhibitor in plasma and is the archetype of the serine protease inhibitor superfamily. Genetic variants of human alpha(1)-antitrypsin are associated with early-onset emphysema and liver cirrhosis. However, the detailed molecular mechanism for the pathogenicity of most variant alpha(1)-antitrypsin molecules is not known. Here we examined the structural basis of a dozen deficient alpha(1)-antitrypsin variants. Unlike most alpha(1)-antitrypsin variants, which were unstable, D256V and L41P variants exhibited extremely retarded protein folding as compared with the wild-type molecule. Once folded, however, the stability and inhibitory activity of these variant proteins were comparable to those of the wild-type molecule. Retarded protein folding may promote protein aggregation by allowing the accumulation of aggregation-prone folding intermediates. Repeated observations of retarded protein folding indicate that it is an important mechanism causing alpha(1)-antitrypsin deficiency by variant molecules, which have to fold into the metastable native form to be functional.
Jung
Chan-Hun
CH
Department of Molecular Biology, Sejong University, 98 Gunja-dong, Kwangjin-gu, Seoul 143-747, Korea.
Na
Yu-Ran
YR
Im
Hana
H
D000818:Animals; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D006801:Humans; D019272:Leukocyte Elastase / Q000037:antagonists & inhibitors / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense / Q000235:genetics*; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors / Q000378:metabolism; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013552:Swine; D013816:Thermodynamics; D013997:Time Factors; D014508:Urea / Q000737:chemistry; D000515:alpha 1-Antitrypsin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D000515:alpha 1-Antitrypsin; D014508:Urea; D010196:Pancreatic Elastase; D019272:Leukocyte Elastase