Key result
Modification of actin subdomain 1 by N-ethylmaleimide inhibits alpha-actinin-induced bundling of actin filaments, likely due to spatial reorganization of actin monomers.
NEM modification of actin Cys-374 inhibits alpha-actinin-induced bundling by inducing spatial reorganization of actin monomers.
No clinical implications yet; leaves open effects of actin modification on myofilament function in vivo.
We show that the modification of actin subdomain 1 by N-ethylmaleimide (NEM), which binds Cys-374 close to the C-terminus of the molecule, inhibits the alpha-actinin-induced bundling of actin filaments. This effect is not merely related to the block of Cys-374, since N-(1-pyrenyl)iodoacetamide (pyrene-IA) is unable to prevent bundling. Considering that NEM (but not pyrene-IA) influences actin assembly, we suggest that the inhibition of the actin-alpha-actinin interaction is due to the chemical modification of actin Cys-374 which, by inducing a marked spatial reorganization of actin monomers, is able to modify both the intra- and inter-molecular interactions of this protein. Finally, NEM-modified actin filaments form bundles in the presence of polyethylene glycol 6000 since, in this case, the side by side association of actin filaments does not depend on the accessibility of binding sites nor on the formation of chemical bonds.
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Milzani et al. (1995) studied In vitro actin filament assembly. N-ethylmaleimide (NEM) modification vs. N-(1-pyrenyl)iodoacetamide (pyrene-IA) modification was evaluated on alpha-actinin-induced bundling of actin filaments. Modification of actin subdomain 1 by N-ethylmaleimide inhibits alpha-actinin-induced bundling of actin filaments, likely due to spatial reorganization of actin monomers.
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