Title:Chaperone-like activity of monomeric human 14-3-3zeta on different protein substrates.
Authors:Sluchanko NN; Roman SG; Chebotareva NA; Gusev NB
Publication:Arch Biochem Biophys. 2014 May 1;549:32-9. doi: 10.1016/ Epub 2014 Mar 26.
Members of the 14-3-3 protein family interact with hundreds of different, predominantly phosphorylated, proteins. 14-3-3 dimers are prevalent but exist at the equilibrium with the monomers. Our previous studies using the engineered monomeric 14-3-3zeta (14-3-3zetam) showed that 14-3-3zeta monomer retained binding activity towards selected phosphorylated partners and, in addition, it prevented heat-induced aggregation of myosin subfragment 1. Since the chaperone-like activity of 14-3-3 monomers has been insufficiently studied, here we have analyzed the effect of 14-3-3zetam on the aggregation of different model proteins. We found that 14-3-3zetam demonstrated considerable chaperone-like activity by inhibiting the DTT-induced aggregation of insulin and thermally-induced aggregation of alcohol dehydrogenase and phosphorylase kinase. Importantly, the anti-aggregating activity of 14-3-3zetam was concentration-dependent and overall, was more pronounced than that of its dimeric counterpart. In some cases, the chaperone-like effect of 14-3-3zetam was comparable, or even higher, than that of the small heat shock proteins, HspB6 and HspB5. We suggest that 14-3-3s not only can bind and regulate the activity of multiple phosphoproteins, but also possess moonlighting chaperone-like activity, which is especially pronounced in the case of monomeric forms of 14-3-3 which can be present under certain stress conditions.