Kinetic instability of the serpin Z alpha1-antitrypsin promotes aggregation

Anja S Knaupp, Vitalina Levina, Amy Louise Robertson, Mary Catherine Pearce, Stephen Paul Bottomley

Research output: Contribution to journalArticleResearchpeer-review

38 Citations (Scopus)

Abstract

The serpinopathies encompass a large number of diseases caused by inappropriate conformational change and self-association (polymerization) of a serpin (serine proteinase inhibitor) molecule. The most common serpinopathy is alpha(1)-antitrypsin (alpha(1)AT) deficiency, which is associated with an increased risk for liver cirrhosis, hepatocellular carcinoma and early-onset emphysema. The Z variant of alpha(1)AT, which accounts for 95 of all cases of alpha(1)AT deficiency, polymerizes during synthesis and after secretion. Here, we show using intrinsic and extrinsic fluorescence probes that Z alpha(1)AT exists in a non-native conformation. We examined the thermodynamic stability by transverse urea gradient gel electrophoresis, thermal denaturation and equilibrium guanidine hydrochloride unfolding and found that, despite structural differences between the two proteins, wild-type alpha(1)AT and Z alpha(1)AT display similar unfolding pathways and thermodynamic stabilities. Far-UV circular dichroism and bis-ANS (4,4 -dianilino-1,1 -binaphthyl-5,5 -disulfonic acid, dipotassium salt) fluorescence suggest that the intermediate ensembles formed during unfolding of wild-type alpha(1)AT and Z alpha(1)AT are characterized by similar structural features. Kinetic analysis of the unfolding transition showed that Z alpha(1)AT unfolds at least 1.5-fold faster than the wild type. The biological implications of these data are discussed.
Original languageEnglish
Pages (from-to)375 - 383
Number of pages9
JournalJournal of Molecular Biology
Volume396
Issue number2
DOIs
Publication statusPublished - 2010

Cite this