Metallothionein-3 attenuates the effect of Cu2+ ions on actin filaments.

Rabina Lakha, Carla Hachicho, Matthew R Mehlenbacher, Dean E Wilcox, Rachel N Austin, Christina L Vizcarra

Journal of inorganic biochemistry 2023 May

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Metallothionein 3 (MT-3) is a cysteine-rich metal-binding protein that is expressed in the mammalian central nervous system and kidney. Various reports have posited a role for MT-3 in regulating the actin cytoskeleton by promoting the assembly of actin filaments. We generated purified, recombinant mouse MT-3 of known metal compositions, either with zinc (Zn), lead (Pb), or copper/zinc (Cu/Zn) bound. None of these forms of MT-3 accelerated actin filament polymerization in vitro, either with or without the actin binding protein profilin. Furthermore, using a co-sedimentation assay, we did not observe Zn-bound MT-3 in complex with actin filaments. Cu2+ ions on their own induced rapid actin polymerization, an effect that we attribute to filament fragmentation. This effect of Cu2+ is reversed by adding either EGTA or Zn-bound MT-3, indicating that either molecule can chelate Cu2+ from actin. Altogether, our data indicate that purified recombinant MT-3 does not directly bind actin but it does attenuate the Cu-induced fragmentation of actin filaments. Copyright © 2023 Elsevier Inc. All rights reserved.

Citation

Rabina Lakha, Carla Hachicho, Matthew R Mehlenbacher, Dean E Wilcox, Rachel N Austin, Christina L Vizcarra. Metallothionein-3 attenuates the effect of Cu2+ ions on actin filaments. Journal of inorganic biochemistry. 2023 May;242:112157