title: Destabilization of apoprotein is insufficient to explain Cu,Zn-superoxide dismutase-linked ALS pathogenesis.
abstract: The relative stabilities and structural properties of a representative set of 20 ALS-mutant Cu,Zn-superoxide dismutase apoproteins were examined by using differential scanning calorimetry and hydrogen-deuterium (H/D) exchange followed by MS. Contrary to recent reports from other laboratories, we found that ALS-mutant apoproteins are not universally destabilized by the disease-causing mutations. For example, several of the apoproteins with substitutions at or near the metal binding region (MBR) (MBR mutants) exhibited melting temperatures (Tm) in the range 51.6 degrees C to 56.2 degrees C, i.e., similar to or higher than that of the WT apoprotein (Tm = 52.5 degrees C). The apoproteins with substitutions remote from the MBR (WT-like mutants) showed a wide range of Tms, 40.0 degrees C to 52.4 degrees C. The H/D exchange properties of the mutants were also wide-ranging: the MBR mutant apoproteins exhibited H/D exchange kinetics similar to the WT apoprotein, as did some of the more stable WT-like mutant apoproteins, whereas the less stable apoproteins exhibited significantly less protection from H/D exchange than the WT apoprotein. Most striking were the three mutant apoproteins, D101N, E100K, and N139K, which have apparently normal metallation properties, and differ little from the WT apoprotein in either thermal stability or H/D exchange kinetics. Thus, the ALS mutant Cu,Zn-superoxide dismutase apoproteins do not all share reduced global stability, and additional properties must be identified and understood to explain the toxicity of all of the mutant proteins.
authors: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
authors: Jorge A
authors: JA
authors: Rodriguez
authors: Bryan Francis
authors: BF
authors: Shaw
authors: Armando
authors: A
authors: Durazo
authors: Se Hui
authors: SH
authors: Sohn
authors: Peter A
authors: PA
authors: Doucette
authors: Aram M
authors: AM
authors: Nersissian
authors: Kym F
authors: KF
authors: Faull
authors: Daryl K
authors: DK
authors: Eggers
authors: Ashutosh
authors: A
authors: Tiwari
authors: Lawrence J
authors: LJ
authors: Hayward
authors: Joan Selverstone
authors: JS
authors: Valentine
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D041961:Deuterium Exchange Measurement; D006801:Humans; D013058:Mass Spectrometry; D008670:Metals / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D044366:Transition Temperature
chemical_list: D008670:Metals; C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1