title: Role of disulfide cross-linking of mutant SOD1 in the formation of inclusion-body-like structures.
abstract: BACKGROUND
  Pathologic aggregates of superoxide dismutase 1 (SOD1) harboring mutations linked to familial amyotrophic lateral sclerosis (fALS) have been shown to contain aberrant intermolecular disulfide cross-links. In prior studies, we observed that intermolecular bonding was not necessary in the formation of detergent- insoluble SOD1 complexes by mutant SOD1, but we were unable to assess whether this type of bonding may be important for pathologic inclusion formation. In the present study, we visually assess the formation of large inclusions by fusing mutant SOD1 to yellow fluorescent protein (YFP).
  
  
  RESULTS
  Experimental constructs possessing mutations at all cysteine residues in SOD1 (sites 6, 57, 111, and 146 to F,S,Y,R or G,S,Y,R, respectively) were shown to maintain a high propensity of inclusion formation despite the inability to form disulfide cross-links. Interestingly, although aggregates form when all cysteines were mutated, double mutants of the ALS mutation C6G with an experimental mutation C111S exhibited low aggregation propensity.
  
  
  CONCLUSIONS
  Overall, this study is an extension of previous work demonstrating that cysteine residues in mutant SOD1 play a role in modulating aggregation and that intermolecular disulfide bonds are not required to produce large intracellular inclusion-like structures.
authors.affiliation: Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, SantaFe HealthCare Alzheimer's Disease Research Center, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Brittany L T
authors.initials: BL
authors.lastname: Roberts
authors.forename: Kinaree
authors.initials: K
authors.lastname: Patel
authors.forename: Hilda H
authors.initials: HH
authors.lastname: Brown
authors.forename: David R
authors.initials: DR
authors.lastname: Borchelt
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins; D016466:CHO Cells; D006224:Cricetinae; D003432:Cross-Linking Reagents / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D004195:Disease Models, Animal; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism; D008164:Luminescent Proteins; D009154:Mutation; D017510:Protein Folding; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1
chemical_list: D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D004220:Disulfides; D008164:Luminescent Proteins; C000606290:SOD1 protein, human; C054562:yellow fluorescent protein, Bacteria; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D003545:Cysteine