Abstract
Human cystatin C (HCC), a cysteine-protease inhibitor, exists as a folded monomer under physiological conditions but has the ability to self-assemble via domain swapping into multimeric states, including oligomers with a doughnut-like structure. The structure of the monomeric HCC has been solved by X-ray crystallography, and a covalently linked version of HCC (stab-1 HCC) is able to form stable oligomeric species containing 10–12 monomeric subunits. We have performed molecular modeling, and in conjunction with experimental parameters obtained from atomic force microscopy (AFM), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) measurements, we observe that the structures are essentially flat, with a height of about 2 nm, and the distance between the outer edge of the ring and the edge of the central cavity is ~5.1 nm. These dimensions correspond to the height and diameter of one stab-1 HCC subunit and we present a dodecamer model for stabilized cystatin C oligomers using molecular dynamics simulations and experimentally measured parameters. Given that oligomeric species in protein aggregation reactions are often transient and very highly heterogeneous, the structural information presented here on these isolated stab-1 HCC oligomers may be useful to further explore the physiological relevance of different structural species of cystatin C in relation to protein misfolding disease.
Highlights
Human cystatin C (HCC), containing 120 amino acids, belongs to the cystatin type 2 superfamily [1,2], and is a potent inhibitor of papain-like (C1) and legumain-like (C13) cysteine-proteases [3,4]
Though less commonly observed than other types of structures, doughnut-like oligomeric forms have been reported for human cystatin C (HCC) [31] and other amyloidogenic proteins, including α-synuclein, the amyloid β (Aβ) peptide and immunoglobulin light chains [32,33,34]
The aim of this present study is to define a structural model of the stable human cystatin C oligomers by combining information from the crystal structure of monomeric stab-1 HCC [14], along with experimental measurements of the oligomers obtained using transmission electron microscopy (TEM), atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) techniques, with molecular dynamics (MD) simulations
Summary
Human cystatin C (HCC), containing 120 amino acids, belongs to the cystatin type 2 superfamily [1,2], and is a potent inhibitor of papain-like (C1) and legumain-like (C13) cysteine-proteases [3,4]. Though less commonly observed than other types of structures, doughnut-like oligomeric forms have been reported for human cystatin C (HCC) [31] and other amyloidogenic proteins, including α-synuclein, the amyloid β (Aβ) peptide and immunoglobulin light chains [32,33,34] The aim of this present study is to define a structural model of the stable human cystatin C oligomers by combining information from the crystal structure of monomeric stab-1 HCC [14], along with experimental measurements of the oligomers obtained using transmission electron microscopy (TEM), atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) techniques, with molecular dynamics (MD) simulations. We propose a dodecamer model of the stab-1 cystatin C oligomers
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
