Several proteins imported into chloroplasts form stable complexes with the GroEL-related chloroplast molecular chaperone.

AUTOR(ES)

Lubben, T H

RESUMO

Nine different proteins were imported into isolated pea chloroplasts in vitro. For seven of these [the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), beta-subunit of ATP synthase, glutamine synthetase, the light-harvesting chlorophyll a/b binding protein, chloramphenicol acetyltransferase, and pre-beta-lactamase], a fraction was found to migrate as a stable high-molecular-weight complex during nondenaturing gel electrophoresis. This complex contained the mature forms of the imported proteins and the groEL-related chloroplast chaperonin 60 (previously known as Rubisco subunit binding protein). Thus, the stable association of imported proteins with this molecular chaperone is widespread and not necessarily restricted to Rubisco subunits or to chloroplast proteins. With two of the imported proteins (ferredoxin and superoxide dismutase), such complexes were not observed. It seems likely that, in addition to its proposed role in assembly of Rubisco, the chloroplast chaperonin 60 is involved in the assembly or folding of a wide range of proteins in chloroplasts.

Documentos Relacionados

• Three pure chaperone proteins of Escherichia coli--SecB, trigger factor and GroEL--form soluble complexes with precursor proteins in vitro.
• Alpha-crystallin can function as a molecular chaperone.
• Molecular Analysis of the Multiple GroEL Proteins of Chlamydiae
• The potent bone-resorbing mediator of Actinobacillus actinomycetemcomitans is homologous to the molecular chaperone GroEL.
• Folding with and without encapsulation by cis- and trans-only GroEL–GroES complexes