A strong protein unfolding activity is associated with the binding of precursor chloroplast proteins to chloroplast envelopes.
Plant Mol Biol
; 23(2): 309-24, 1993 Oct.
Article
en En
| MEDLINE
| ID: mdl-8219067
ABSTRACT
Protein conformational changes related to transport into chloroplasts have been studied. Two chimaeric proteins carrying the transit peptide of either ferredoxin or plastocyanin linked to the mouse cytosolic enzyme dihydrofolate reductase (EC 1.5.1.3.) were employed. In contrast to observations in mitochondria, we found in chloroplasts that transport of a purified ferredoxin-dihydrofolate reductase fusion protein is not blocked by the presence of methotrexate, a folate analogue that stabilizes the structural conformation of dihydrofolate reductase. It is shown that transport competence of this protein in the presence of methotrexate is not a consequence of alteration of the folding characteristics or methotrexate binding properties of dihydrofolate reductase by fusion to the ferredoxin transit peptide. Binding of dihydrofolate reductase fusion proteins to chloroplast envelopes is not inhibited by low temperature and it is only partially diminished by methotrexate. It is demonstrated that the dihydrofolate reductase fusion proteins unfold, despite the presence of methotrexate, on binding to the chloroplast envelopes. We propose the existence of a strong protein unfolding activity associated to the chloroplast envelopes.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Plantas
/
Precursores de Proteínas
/
Tetrahidrofolato Deshidrogenasa
/
Señales de Clasificación de Proteína
/
Cloroplastos
/
Ferredoxinas
Tipo de estudio:
Prognostic_studies
/
Risk_factors_studies
Idioma:
En
Revista:
Plant Mol Biol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
BOTANICA
Año:
1993
Tipo del documento:
Article
País de afiliación:
Francia