Chaperone Activation and Client Binding of a 2-Cysteine Peroxiredoxin

ABSTRACT: Many 2-Cys-peroxiredoxins (2-Cys-Prxs) serve as dual-function proteins. Active as peroxidases under non-stress conditions, they convert into effective chaperones under stress conditions. While their peroxidase activity has been extensively studied and shown to involve cycles of redox-mediated oligomeric changes, the mechanisms by which 2-Cys-Prxs sense stress and convert into general chaperones remain to be defined. Here we focus on the Leishmania infantum mitochondrial 2-Cys-Prx (mTXNPx, Prx1m), which, in its reduced, decameric form, readily adopts chaperone function upon exposure to heat shock temperatures. This activity is crucial for parasite survival in mammalian hosts. Here we have determined the cryo-EM structure of mTXNPx in complex with a thermally unfolded client protein that identifies the flexible N-termini of mTXNPx to form a well-resolved central belt that contacts and encapsulates the unstructured client protein in the center of the decamer ring. In vivo cross-linking studies combined with quantitative in vitro cross-linking experiments further support these interactions, and demonstrate that mTXNPx decamers undergo substantial temperature-dependent structural rearrangements specifically at the dimer-dimer interfaces. These structural changes appear crucial for exposing chaperone client binding sites that are otherwise buried in the peroxidase-active protein. Based on this mechanism, we propose that mTXNPx is the founding member of heat-stress activated chaperones in parasitic mitochondria that facilitate the transition to warm-blooded host environments.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Photinus Pyralis (common Eastern Firefly) (lampyris Pyralis) Leishmania Infantum

SUBMITTER: Karl Makepeace  

LAB HEAD: Christoph H. Borchers

PROVIDER: PXD010281 | Pride | 2019-02-19

REPOSITORIES: Pride