Document Detail


Structural and functional characterization of a highly specific serpin in the insect innate immunity.
MedLine Citation:
PMID:  21047786     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The Toll signaling pathway, an essential innate immune response in invertebrates, is mediated via the serine protease cascade. Once activated, the serine proteases are irreversibly inactivated by serine protease inhibitors (serpins). Recently, we identified three serpin-serine protease pairs that are directly involved in the regulation of Toll signaling cascade in a large beetle, Tenebrio molitor. Of these, the serpin SPN48 was cleaved by its target serine protease, Spätzle-processing enzyme, at a noncanonical P1 residue of the serpin's reactive center loop. To address this unique cleavage, we report the crystal structure of SPN48, revealing that SPN48 exhibits a native conformation of human antithrombin, where the reactive center loop is partially inserted into the center of the largest β-sheet of SPN48. The crystal structure also shows that SPN48 has a putative heparin-binding site that is distinct from those of the mammalian serpins. Ensuing biochemical studies demonstrate that heparin accelerates the inhibition of Spätzle-processing enzyme by a proximity effect in targeting the SPN48. Our finding provides the molecular mechanism of how serpins tightly regulate innate immune responses in invertebrates.
Authors:
Sun Hee Park; Rui Jiang; Shunfu Piao; Bing Zhang; Eun-Hye Kim; Hyun-Mi Kwon; Xiao Ling Jin; Bok Luel Lee; Nam-Chul Ha
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-11-03
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  286     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-10     Completed Date:  2011-03-02     Revised Date:  2012-01-16    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1567-75     Citation Subset:  IM    
Affiliation:
College of Pharmacy and Research Institute for Drug Development, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea.
Data Bank Information
Bank Name/Acc. No.:
PDB/3OZQ
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Animals
Antithrombins / chemistry,  metabolism
Binding Sites / genetics,  immunology
Calcium / metabolism
Crystallography
Enzyme Activation / immunology
Heparin / metabolism
Humans
Immunity, Innate / physiology*
Molecular Sequence Data
Mutagenesis, Site-Directed
Protein Structure, Tertiary
Serpins* / genetics,  immunology,  metabolism
Signal Transduction / immunology
Structure-Activity Relationship
Substrate Specificity
Tenebrio / enzymology*,  immunology*
Toll-Like Receptors / immunology,  metabolism
Chemical
Reg. No./Substance:
0/Antithrombins; 0/Serpins; 0/Toll-Like Receptors; 7440-70-2/Calcium; 9005-49-6/Heparin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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