Leporipoxvirus Cu,Zn-superoxide dismutase (SOD) homologs are catalytically inert decoy proteins that bind copper chaperone for SOD

Melissa L.T. Teoh, Paula J. Walasek, David H. Evans

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Many Chordopoxviruses encode catalytically inactive homologs of cellular Cu-Zn superoxide dismutase (SOD). The biological function of these proteins is unknown, although the proteins encoded by Leporipoxviruses have been shown to promote a slow decline in the level of superoxide dismutase activity in virus-infected cells. To gain more insights into their function, we have further characterized the enzymatic and biochemical properties of a SOD homolog encoded by Shope fibroma virus. Shope fibroma virus SOD has retained the zinc binding properties of its cellular homolog, but cannot bind copper. Site-directed mutagenesis showed that it requires at least four amino acid substitutions to partially restore copper binding activity, but even these changes still did not restore catalytic activity. Reciprocal co-immunoprecipitation experiments showed that recombinant Shope fibroma virus SOD forms very stable complexes with cellular copper chaperones for SOD and these observations were confirmed using glutathione-S-transferase tagged proteins. Similar viral SOD/chaperone complexes were formed in cells infected with a closely related myxoma virus, where we also noted that some of the SOD antigen co-localizes with mitochondrial markers using confocal fluorescence microscopy. About 2% of the viral SOD was subsequently detected in gradient-purified mitochondria extracted from virus-infected cells. These poxviral SOD homologs do not form stable complexes with cellular Cu,Zn-SOD or affect its concentration. We suggest that Leporipoxvirus SOD homologs are catalytically inert decoy proteins that are designed to interfere in the proper metallation and activation of cellular Cu,Zn-SOD. This reaction might be advantageous for tumorigenic poxviruses, since higher levels of superoxide have been proposed to have antiapoptotic and tumorigenic activity.

Original languageEnglish (US)
Pages (from-to)33175-33184
Number of pages10
JournalJournal of Biological Chemistry
Volume278
Issue number35
DOIs
StatePublished - Aug 29 2003

Fingerprint

Leporipoxvirus
Superoxide Dismutase
Copper
Viruses
Rabbit Fibroma Virus
Proteins
Myxoma virus
Poxviridae
Superoxide Dismutase-1
Mutagenesis
Mitochondria
Amino Acid Substitution
Confocal microscopy
Site-Directed Mutagenesis
Fluorescence microscopy
Glutathione Transferase
Fluorescence Microscopy
Immunoprecipitation
Confocal Microscopy
Superoxides

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Leporipoxvirus Cu,Zn-superoxide dismutase (SOD) homologs are catalytically inert decoy proteins that bind copper chaperone for SOD. / Teoh, Melissa L.T.; Walasek, Paula J.; Evans, David H.

In: Journal of Biological Chemistry, Vol. 278, No. 35, 29.08.2003, p. 33175-33184.

Research output: Contribution to journalArticle

@article{bfcf80e933814e3a803a3cf7b38684c1,
title = "Leporipoxvirus Cu,Zn-superoxide dismutase (SOD) homologs are catalytically inert decoy proteins that bind copper chaperone for SOD",
abstract = "Many Chordopoxviruses encode catalytically inactive homologs of cellular Cu-Zn superoxide dismutase (SOD). The biological function of these proteins is unknown, although the proteins encoded by Leporipoxviruses have been shown to promote a slow decline in the level of superoxide dismutase activity in virus-infected cells. To gain more insights into their function, we have further characterized the enzymatic and biochemical properties of a SOD homolog encoded by Shope fibroma virus. Shope fibroma virus SOD has retained the zinc binding properties of its cellular homolog, but cannot bind copper. Site-directed mutagenesis showed that it requires at least four amino acid substitutions to partially restore copper binding activity, but even these changes still did not restore catalytic activity. Reciprocal co-immunoprecipitation experiments showed that recombinant Shope fibroma virus SOD forms very stable complexes with cellular copper chaperones for SOD and these observations were confirmed using glutathione-S-transferase tagged proteins. Similar viral SOD/chaperone complexes were formed in cells infected with a closely related myxoma virus, where we also noted that some of the SOD antigen co-localizes with mitochondrial markers using confocal fluorescence microscopy. About 2{\%} of the viral SOD was subsequently detected in gradient-purified mitochondria extracted from virus-infected cells. These poxviral SOD homologs do not form stable complexes with cellular Cu,Zn-SOD or affect its concentration. We suggest that Leporipoxvirus SOD homologs are catalytically inert decoy proteins that are designed to interfere in the proper metallation and activation of cellular Cu,Zn-SOD. This reaction might be advantageous for tumorigenic poxviruses, since higher levels of superoxide have been proposed to have antiapoptotic and tumorigenic activity.",
author = "Teoh, {Melissa L.T.} and Walasek, {Paula J.} and Evans, {David H.}",
year = "2003",
month = "8",
day = "29",
doi = "10.1074/jbc.M300644200",
language = "English (US)",
volume = "278",
pages = "33175--33184",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "35",

}

TY - JOUR

T1 - Leporipoxvirus Cu,Zn-superoxide dismutase (SOD) homologs are catalytically inert decoy proteins that bind copper chaperone for SOD

AU - Teoh, Melissa L.T.

AU - Walasek, Paula J.

AU - Evans, David H.

PY - 2003/8/29

Y1 - 2003/8/29

N2 - Many Chordopoxviruses encode catalytically inactive homologs of cellular Cu-Zn superoxide dismutase (SOD). The biological function of these proteins is unknown, although the proteins encoded by Leporipoxviruses have been shown to promote a slow decline in the level of superoxide dismutase activity in virus-infected cells. To gain more insights into their function, we have further characterized the enzymatic and biochemical properties of a SOD homolog encoded by Shope fibroma virus. Shope fibroma virus SOD has retained the zinc binding properties of its cellular homolog, but cannot bind copper. Site-directed mutagenesis showed that it requires at least four amino acid substitutions to partially restore copper binding activity, but even these changes still did not restore catalytic activity. Reciprocal co-immunoprecipitation experiments showed that recombinant Shope fibroma virus SOD forms very stable complexes with cellular copper chaperones for SOD and these observations were confirmed using glutathione-S-transferase tagged proteins. Similar viral SOD/chaperone complexes were formed in cells infected with a closely related myxoma virus, where we also noted that some of the SOD antigen co-localizes with mitochondrial markers using confocal fluorescence microscopy. About 2% of the viral SOD was subsequently detected in gradient-purified mitochondria extracted from virus-infected cells. These poxviral SOD homologs do not form stable complexes with cellular Cu,Zn-SOD or affect its concentration. We suggest that Leporipoxvirus SOD homologs are catalytically inert decoy proteins that are designed to interfere in the proper metallation and activation of cellular Cu,Zn-SOD. This reaction might be advantageous for tumorigenic poxviruses, since higher levels of superoxide have been proposed to have antiapoptotic and tumorigenic activity.

AB - Many Chordopoxviruses encode catalytically inactive homologs of cellular Cu-Zn superoxide dismutase (SOD). The biological function of these proteins is unknown, although the proteins encoded by Leporipoxviruses have been shown to promote a slow decline in the level of superoxide dismutase activity in virus-infected cells. To gain more insights into their function, we have further characterized the enzymatic and biochemical properties of a SOD homolog encoded by Shope fibroma virus. Shope fibroma virus SOD has retained the zinc binding properties of its cellular homolog, but cannot bind copper. Site-directed mutagenesis showed that it requires at least four amino acid substitutions to partially restore copper binding activity, but even these changes still did not restore catalytic activity. Reciprocal co-immunoprecipitation experiments showed that recombinant Shope fibroma virus SOD forms very stable complexes with cellular copper chaperones for SOD and these observations were confirmed using glutathione-S-transferase tagged proteins. Similar viral SOD/chaperone complexes were formed in cells infected with a closely related myxoma virus, where we also noted that some of the SOD antigen co-localizes with mitochondrial markers using confocal fluorescence microscopy. About 2% of the viral SOD was subsequently detected in gradient-purified mitochondria extracted from virus-infected cells. These poxviral SOD homologs do not form stable complexes with cellular Cu,Zn-SOD or affect its concentration. We suggest that Leporipoxvirus SOD homologs are catalytically inert decoy proteins that are designed to interfere in the proper metallation and activation of cellular Cu,Zn-SOD. This reaction might be advantageous for tumorigenic poxviruses, since higher levels of superoxide have been proposed to have antiapoptotic and tumorigenic activity.

UR - http://www.scopus.com/inward/record.url?scp=0041856214&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0041856214&partnerID=8YFLogxK

U2 - 10.1074/jbc.M300644200

DO - 10.1074/jbc.M300644200

M3 - Article

C2 - 12773543

AN - SCOPUS:0041856214

VL - 278

SP - 33175

EP - 33184

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 35

ER -