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bioRxiv · 10.1101/2022.09.23.509211

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

Lakha, R.·Hachicho, C.·Mehlenbacher, M. R.·Wilcox, D. E.·Austin, R. N.·Vizcarra, C. L.
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Abstract

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 recombinant MT-3 does not directly bind actin but it does attenuate the Cu-induced fragmentation of actin filaments.

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Lakha, R., Hachicho, C., Mehlenbacher, M. R., Wilcox, D. E., Austin, R. N., Vizcarra, C. L.. 2022-09-24. Metallothionein-3 attenuates the effect of Cu2+ ions on actin filaments. https://doi.org/10.1101/2022.09.23.509211

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