INVESTIGADORES
ARAN Martin
artículos
Título:
ATP and Mg2+ promote the reversible oligomerization and aggregation of chloroplast 2-Cys peroxiredoxin.
Autor/es:
ARAN M, FERRERO D, WOLOSIUK A, MORA-GARCÍA S, WOLOSIUK RA.
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Referencias:
Lugar: Bethesda, Maryland; Año: 2011 vol. 286 p. 23441 - 23451
ISSN:
0021-9258
Resumen:
2-Cys peroxiredoxins (2-Cys Prxs) are ubiquitous peroxidases with important roles in cellular antioxidant defense and hydrogen
peroxide-mediated signaling. Post-translational
modifications of conserved cysteines cause the transition from low to
high
molecular weight oligomers, triggering the
functional change from peroxidase to molecular chaperone. However, it
remains unclear
how non-covalent interactions of 2-Cys Prx with
metabolites modulate the quaternary structure. Here, we disclose that
ATP
and Mg2+ (ATP/Mg) promote the self-polymerization of chloroplast 2-Cys Prx (polypeptide 23.5 kDa) into soluble higher order assemblies
(>2 MDa) that proceed to insoluble aggregates beyond 5 mm ATP. Remarkably, the withdrawal of ATP or Mg2+
brings soluble oligomers and insoluble aggregates back to the native
conformation without compromising the associated functions.
As confirmed by transmission electron microscopy,
ATP/Mg drive the toroid-like decamers (diameter 13 nm) to the formation
of large sphere-like particles (diameter ∼30 nm).
Circular dichroism studies on ATP-labeled 2-Cys Prx reveal that ATP/Mg
enhance
the proportion of β-sheets with the concurrent
decrease in the content of α-helices. In line with this observation, the
formation
of insoluble aggregates is strongly prevented by
2,2,2-trifluoroethanol, a cosolvent employed to induce α-helical
conformations.
We further find that the response of
self-polymerization to ATP/Mg departs abruptly from that of the
associated peroxidase
and chaperone activities when two highly conserved
residues, Arg129 and Arg152, are mutated.
Collectively, our data uncover that non-covalent interactions of ATP/Mg
with 2-Cys Prx modulate dynamically
the quaternary structure, thereby coupling the
non-redox chemistry of cell energy with redox transformations at
cysteine residues.