Role of salt bridges in the dimer interface of 14-3-3? in dimer dynamics, N-terminal ?-helical order, and molecular chaperone activity.

ABSTRACT: The 14-3-3 family of intracellular proteins are dimeric, multifunctional adaptor proteins that bind to and regulate the activities of many important signaling proteins. The subunits within 14-3-3 dimers are predicted to be stabilized by salt bridges that are largely conserved across the 14-3-3 protein family and allow the different isoforms to form heterodimers. Here, we have examined the contributions of conserved salt-bridging residues in stabilizing the dimeric state of 14-3-3?. Using analytical ultracentrifugation, our results revealed that Asp21 and Glu89 both play key roles in dimer dynamics and contribute to dimer stability. Furthermore, hydrogen-deuterium exchange coupled with mass spectrometry showed that mutation of Asp21 promoted disorder in the N-terminal helices of 14-3-3?, suggesting that this residue plays an important role in maintaining structure across the dimer interface. Intriguingly, a D21N 14-3-3? mutant exhibited enhanced molecular chaperone ability that prevented amorphous protein aggregation, suggesting a potential role for N-terminal disorder in 14-3-3?'s poorly understood chaperone action. Taken together, these results imply that disorder in the N-terminal helices of 14-3-3? is a consequence of the dimer-monomer dynamics and may play a role in conferring chaperone function to 14-3-3? protein.

SUBMITTER: Woodcock JM 

PROVIDER: S-EPMC5766903 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature