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Calpain-resistant fragment(s) of α-synuclein regulates the synuclein-cleaving activity of 20S proteasome

Authors
 Hyun Jin Kim  ;  Daekyun Lee  ;  Choong-Hwan Lee  ;  Kwang Chul Chung  ;  Jongsun Kim  ;  Seung R. Paik 
Citation
 ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, Vol.455(1) : 40-47, 2006 
Journal Title
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
ISSN
 0003-9861 
Issue Date
2006
MeSH
Amino Acid Sequence ; Amino Acid Substitution/genetics ; Amino Acids/genetics ; Amino Acids/metabolism* ; Animals ; Calpain/metabolism* ; Electrophoresis, Polyacrylamide Gel ; Glutamates/genetics ; Glutamates/metabolism ; Hydrolysis ; Models, Biological ; Molecular Sequence Data ; Mutation/genetics ; Proline/genetics ; Proline/metabolism ; Proteasome Endopeptidase Complex/metabolism* ; Serine/genetics ; Serine/metabolism ; Substrate Specificity ; Swine ; Threonine/genetics ; Threonine/metabolism ; alpha-Synuclein/genetics ; alpha-Synuclein/metabolism*
Abstract
α-Synuclein is a pathological component of Parkinson’s disease by participating in Lewy body formation. Imbalance in protein turnover could result in the abnormal protein aggregation responsible for eventual neuronal cell death. This in vitro digestion study showed that both m-calpain and 20S proteasome preferentially hydrolyzed the N-terminal half of α-synuclein, which made the hydrophobic NAC and following acidic C-terminal region resistant against the proteolyses. Since the acidic C-terminal region contains the PEST segment—a protein degradation signal enriched with amino acids of proline (P), glutamate (E), serine (S), and threonine (T)—, the PEST segment has not been processed or even required for the proteolyses. α-Synuclein would be recognized primarily by m-calpain since the common substrate was processed by m-calpain five times more effectively than 20S proteasome with kcat/Km of 1.64 × 104 M−1 s−1 and 0.32 × 104 M−1 s−1, respectively. The N-terminally truncated protease-resistant C-terminal fragment of α-syn61–140 was demonstrated to stimulate the 20S proteasome-mediated breakdown of α-synuclein and its mutant forms of Ala53Thr and Ala30Pro. The stimulation for Ala53Thr, however, was noticeably less efficient than those for the other proteins, which might support the previous observation of the prolonged intracellular life span of Ala53Thr by 1.5-fold compared to that of wild-type form. We have hypothesized that the N-terminally truncated C-terminal fragment derived from the abundant α-synuclein through intracellular proteolyses could be involved in various physiological or pathological effects which might be related to the formation of abnormal protein aggregation and subsequent neuronal degeneration by influencing the intracellular protein turnover or directly participating in the aggregate formation.
Full Text
http://www.sciencedirect.com/science/article/pii/S0003986106003092
DOI
10.1016/j.abb.2006.08.019
Appears in Collections:
1. College of Medicine (의과대학) > Dept. of Microbiology (미생물학교실) > 1. Journal Papers
Yonsei Authors
Kim, Jong Sun(김종선) ORCID logo https://orcid.org/0000-0002-3149-669X
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/110783
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