Trimeric structure and conformational equilibrium of M-ficolin fibrinogen-like domain

Ficolins are pathogen‐recognition molecules in innate immune systems. The crystal structure of the human M‐ficolin recognition domain (FD1) has been determined at 1.9 Å resolution, and compared with that of the human fibrinogen γ fragment, tachylectin‐5A, L‐ficolin and H‐ficolin. The overall structu...

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Bibliographic Details
Published in:Journal of synchrotron radiation 2008-05, Vol.15 (3), p.243-245
Main Authors: Tanio, Michikazu, Kondo, Shin, Sugio, Shigetoshi, Kohno, Toshiyuki
Format: Article
Language:English
Subjects:
Biopolymers - chemistry
conformational equilibrium
Diffraction Structural Biology
Fibrinogen - chemistry
ficolin
Ficolins
innate immunity
Lectins - chemistry
Models, Molecular
Protein Conformation
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Summary:Ficolins are pathogen‐recognition molecules in innate immune systems. The crystal structure of the human M‐ficolin recognition domain (FD1) has been determined at 1.9 Å resolution, and compared with that of the human fibrinogen γ fragment, tachylectin‐5A, L‐ficolin and H‐ficolin. The overall structure of FD1 is similar to that of the other proteins, although the peptide bond between Asp282 and Cys283, which is in a predicted ligand‐binding site, is a normal trans bond, unlike the cases of the other proteins. Analysis of the pH‐dependent ligand‐binding activity of FD1 in solution suggested that a conformational equilibrium between active and non‐active forms in the ligand‐binding region, involving cis‐trans isomerization of the Asp282—Cys283 peptide bond, contributes to the discrimination between self and non‐self, and that the pKa values of His284 are 6.1 and 6.3 in the active and non‐active forms, respectively.
ISSN:1600-5775
0909-0495
1600-5775
DOI:10.1107/S0909049507054325