Mutant Neuroserpin (S49P) that causes familial encephalopathy with neuroserpin inclusion bodies is a poor proteinase inhibitor and readily forms polymers in vitro.

Abstract

Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is an autosomal dominant dementia that is characterized by intraneuronal inclusions of mutant neuroserpin. We report here the expression, purification, and characterization of wild-type neuroserpin and neuroserpin containing the S49P mutation that causes FENIB. Wild-type neuroserpin formed SDS-stable complexes with tPA with an association rate constant and K(i) of 1.2 x 10(4) m(-1) s(-1) and 5.8 nm, respectively. In contrast, S49P neuroserpin formed unstable complexes with an association rate constant and K(i) of 0.3 x 10(4) m(-1) s(-1) and 533.3 nm, respectively. An assessment by circular dichroism showed that S49P neuroserpin had a lower melting temperature than wild-type protein (49.9 and 56.6 degrees C, respectively) and more readily formed loop-sheet polymers under physiological conditions. Neither the wild-type nor S49P neuroserpin accepted the P7-P2 alpha(1)-anti-trypsin or P14-P3 antithrombin-reactive loop peptides that have been shown to block polymer formation in other members of the serpin superfamily. Taken together, these data demonstrate that S49P neuroserpin is a poor proteinase inhibitor and readily forms loop-sheet polymers. These findings provide strong support for the role of neuroserpin polymerization in the formation of the intraneuronal inclusions that are characteristic of FENIB.

• Authors: Didier Belorgey, Damian C Crowther, Ravi Mahadeva, David A Lomas
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 277 Issue 19 Pg. 17367-73 (May 10 2002) ISSN: 0021-9258 [Print] United States
• PMID: 11880376 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA, Complementary
• Enzyme Inhibitors
• Neuropeptides
• Polymers
• Recombinant Proteins
• Serpins
• neuroserpin

Topics

• Circular Dichroism
• DNA, Complementary (metabolism)
• Dementia (genetics)
• Electrophoresis, Polyacrylamide Gel
• Enzyme Inhibitors (pharmacology)
• Humans
• Kinetics
• Mutagenesis, Site-Directed
• Mutation
• Neuropeptides (chemistry, genetics, metabolism)
• Polymers (chemistry)
• Protein Binding
• Recombinant Proteins (metabolism)
• Serpins (chemistry, genetics, metabolism)
• Time Factors
• Ultraviolet Rays