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Assisted protein folding at low temperature: evolutionaryadaptation of the Antarctic fish chaperonin CCT and its clientproteins


Abstract: Eukaryotic ectotherms of the Southern Ocean face energetic challenges to protein folding assisted by the cytosolic chaperonin CCT. We hypothesize that CCT and its client proteins (CPs) have co-evolved molecular adaptations that facilitate CCT–CP interaction and the ATP-driven folding cycle at low temperature. To test this hypothesis, we compared the functional and structural properties of CCT–CP systems from testis tissues of an Antarctic fish, Gobionotothen gibberifrons (Lo¨nnberg) (habitat/body T521.9 to +2˚C), and of the cow (body T537˚C). We examined the temperature dependence of the binding of denatured CPs (bactin, b-tubulin) by fish and bovine CCTs, both in homologous and heterologous combinations and at temperatures between 24˚C and 20˚C, in a buffer conducive to binding of the denatured CP to the open conformation of CCT. In homologous combination, the percentage of G. gibberifrons CCT bound to CP declined linearly with increasing temperature, whereas the converse was true for bovine CCT. Binding of CCT to heterologous CPs was low, irrespective of temperature. When reactions were supplemented with ATP, G. gibberifrons CCT catalyzed the folding and release of actin at 2˚C. The ATPase activity of apo-CCT from G. gibberifrons at 4˚C was ,2.5-fold greater than that of apo-bovine CCT, whereas equivalent activities were observed at 20˚C. Based on these results, we conclude that the catalytic folding cycle of CCT from Antarctic fishes is partially compensated at their habitat temperature, probably by means of enhanced CP-binding affinity and increased flexibility of the CCT subunits.

 Fuente: Biology Open 2014 Apr 15; 3(4): 261–270

Editorial: The Company of Biologists Ltd

 Fecha de publicación: 15/04/2014

Nº de páginas: 10

Tipo de publicación: Artículo de Revista

DOI: 10.1242/bio.20147427

ISSN: 2046-6390

Url de la publicación: http://bio.biologists.org/content/3/4/261.long

Autores/as

CUELLAR, JORGE
YÉBENES, HUGO
PARKER, SANDRA K.
GERARDO CARRANZA FERRER
SERNA, MARINA
VALPUESTA MORALEJO, JOSÉ MARÍA
DETRICH, H. WILLIAM