A pH Switch Controls Zinc Binding in Tomato Copper-Zinc Superoxide Dismutase.

ABSTRACT: Copper-zinc superoxide dismutase (SOD1) is a major antioxidant metalloenzyme that protects cells from oxidative damage by superoxide anions (O₂^-). Structural, biophysical, and other characteristics have in the past been compiled for mammalian SOD1s and for the highly homologous fungal and bovine SOD1s. Here, we characterize the biophysical properties of a plant SOD1 from tomato chloroplasts and present several of its crystal structures. The most unusual of these structures is a structure at low pH in which tSOD1 harbors zinc in the copper-binding site but contains no metal in the zinc-binding site. The side chain of D83, normally a zinc ligand, adopts an alternate rotameric conformation to form an unusual bidentate hydrogen bond with the side chain of D124, precluding

SUBMITTER: Sea KW 

PROVIDER: S-EPMC8754426 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature