Abstract
Selenocysteine (Sec) is incorporated into proteins in response to UGA codons. This residue is frequently found at the catalytic sites of oxidoreductases. In this study, we characterized the selenoproteome of an anaerobic bacterium, Clostridium sp. (also known as Alkaliphilus oremlandii) OhILA, and identified 13 selenoprotein genes, five of which have not been previously described. One of the detected selenoproteins was methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that repairs oxidatively damaged methionines in a stereospecific manner. To date, little is known about MsrA from anaerobes. We characterized this selenoprotein MsrA which had a single Sec residue at the catalytic site but no cysteine (Cys) residues in the protein sequence. Its SECIS (Sec insertion sequence) element did not resemble those in Escherichia coli. Although with low translational efficiency, the expression of the Clostridium selenoprotein msrA gene in E. coli could be demonstrated by 75Se metabolic labeling, immunoblot analyses, and enzyme assays, indicating that its SECIS element was recognized by the E. coli Sec insertion machinery. We found that the Sec-containing MsrA exhibited at least a 20-fold higher activity than its Cys mutant form, indicating a critical role of Sec in the catalytic activity of the enzyme. Furthermore, our data revealed that the Clostridium MsrA was inefficiently reducible by thioredoxin, which is a typical reducing agent for MsrA, suggesting the use of alternative electron donors in this anaerobic bacterium that directly act on the selenenic acid intermediate and do not require resolving Cys residues.
| Original language | English |
|---|---|
| Pages (from-to) | 1008-1017 |
| Number of pages | 10 |
| Journal | Proteins: Structure, Function and Bioinformatics |
| Volume | 74 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 2009 Mar 1 |
| Externally published | Yes |
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Keywords
- MsrA
- Oxidoreductase
- SECIS elements
- Selenoproteins
- Thioredoxin
ASJC Scopus subject areas
- Structural Biology
- Biochemistry
- Molecular Biology
Cite this
The selenoproteome of Clostridium sp. OhILAs : Characterization of anaerobic bacterial selenoprotein methionine sulfoxide reductase A. / Kim, Hwa Young; Zhang, Yan; Lee, Byung Cheon; Kim, Jae Ryong; Gladyshev, Vadim N.
In: Proteins: Structure, Function and Bioinformatics, Vol. 74, No. 4, 01.03.2009, p. 1008-1017.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The selenoproteome of Clostridium sp. OhILAs
T2 - Characterization of anaerobic bacterial selenoprotein methionine sulfoxide reductase A
AU - Kim, Hwa Young
AU - Zhang, Yan
AU - Lee, Byung Cheon
AU - Kim, Jae Ryong
AU - Gladyshev, Vadim N.
PY - 2009/3/1
Y1 - 2009/3/1
N2 - Selenocysteine (Sec) is incorporated into proteins in response to UGA codons. This residue is frequently found at the catalytic sites of oxidoreductases. In this study, we characterized the selenoproteome of an anaerobic bacterium, Clostridium sp. (also known as Alkaliphilus oremlandii) OhILA, and identified 13 selenoprotein genes, five of which have not been previously described. One of the detected selenoproteins was methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that repairs oxidatively damaged methionines in a stereospecific manner. To date, little is known about MsrA from anaerobes. We characterized this selenoprotein MsrA which had a single Sec residue at the catalytic site but no cysteine (Cys) residues in the protein sequence. Its SECIS (Sec insertion sequence) element did not resemble those in Escherichia coli. Although with low translational efficiency, the expression of the Clostridium selenoprotein msrA gene in E. coli could be demonstrated by 75Se metabolic labeling, immunoblot analyses, and enzyme assays, indicating that its SECIS element was recognized by the E. coli Sec insertion machinery. We found that the Sec-containing MsrA exhibited at least a 20-fold higher activity than its Cys mutant form, indicating a critical role of Sec in the catalytic activity of the enzyme. Furthermore, our data revealed that the Clostridium MsrA was inefficiently reducible by thioredoxin, which is a typical reducing agent for MsrA, suggesting the use of alternative electron donors in this anaerobic bacterium that directly act on the selenenic acid intermediate and do not require resolving Cys residues.
AB - Selenocysteine (Sec) is incorporated into proteins in response to UGA codons. This residue is frequently found at the catalytic sites of oxidoreductases. In this study, we characterized the selenoproteome of an anaerobic bacterium, Clostridium sp. (also known as Alkaliphilus oremlandii) OhILA, and identified 13 selenoprotein genes, five of which have not been previously described. One of the detected selenoproteins was methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that repairs oxidatively damaged methionines in a stereospecific manner. To date, little is known about MsrA from anaerobes. We characterized this selenoprotein MsrA which had a single Sec residue at the catalytic site but no cysteine (Cys) residues in the protein sequence. Its SECIS (Sec insertion sequence) element did not resemble those in Escherichia coli. Although with low translational efficiency, the expression of the Clostridium selenoprotein msrA gene in E. coli could be demonstrated by 75Se metabolic labeling, immunoblot analyses, and enzyme assays, indicating that its SECIS element was recognized by the E. coli Sec insertion machinery. We found that the Sec-containing MsrA exhibited at least a 20-fold higher activity than its Cys mutant form, indicating a critical role of Sec in the catalytic activity of the enzyme. Furthermore, our data revealed that the Clostridium MsrA was inefficiently reducible by thioredoxin, which is a typical reducing agent for MsrA, suggesting the use of alternative electron donors in this anaerobic bacterium that directly act on the selenenic acid intermediate and do not require resolving Cys residues.
KW - MsrA
KW - Oxidoreductase
KW - SECIS elements
KW - Selenoproteins
KW - Thioredoxin
UR - http://www.scopus.com/inward/record.url?scp=61449267536&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=61449267536&partnerID=8YFLogxK
U2 - 10.1002/prot.22212
DO - 10.1002/prot.22212
M3 - Article
C2 - 18767149
AN - SCOPUS:61449267536
VL - 74
SP - 1008
EP - 1017
JO - Proteins: Structure, Function and Bioinformatics
JF - Proteins: Structure, Function and Bioinformatics
SN - 0887-3585
IS - 4
ER -