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Titolo:
METHOTREXATE DOES NOT BLOCK IMPORT OF A DHFR FUSION PROTEIN INTO CHLOROPLASTS
Autore:
AMERICA T; HAGEMAN J; GUERA A; ROOK F; ARCHER K; KEEGSTRA K; WEISBEEK P;
Indirizzi:
UNIV UTRECHT,DEPT MOLEC CELL BIOL,PADUALAAN 8 3584 CH UTRECHT NETHERLANDS
Titolo Testata:
Plant molecular biology
fascicolo: 2, volume: 24, anno: 1994,
pagine: 283 - 294
SICI:
0167-4412(1994)24:2<283:MDNBIO>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
MITOCHONDRIAL PRECURSOR PROTEIN; HEAT-SHOCK PROTEIN; CYTOSOLIC FACTORS; BINDING-PROTEIN; TRANSIT PEPTIDE; MEMBRANE; TRANSLOCATION; COMPETENCE; CELLS; TRANSPORT;
Keywords:
CHLOROPLAST; DHFR; METHOTREXATE; PRECURSOR; PROTEIN IMPORT; UNFOLDING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
T. America et al., "METHOTREXATE DOES NOT BLOCK IMPORT OF A DHFR FUSION PROTEIN INTO CHLOROPLASTS", Plant molecular biology, 24(2), 1994, pp. 283-294

Abstract

Protein import into chloroplasts requires the movement of a precursorprotein across the envelope membranes. The conformation of a precursor as it passes from the aqueous medium across the hydrophobic membranes is not known in detail. To address this problem we examined precursor conformation during translocation using the chimeric precursor PCDHFR, which contains the plastocyanin (PC) transit peptide in front of mouse cytosolic dihydrofolate reductase (DHFR). The chimeric protein is targeted to chloroplasts and is competent for import. The conformationof PCDHFR can be stabilized by complexing with methotrexate, an analogue of the substrate of DHFR. Methotrexate strongly inhibits DHFR import into yeast mitochondria (M. filers and G. Schatz, Nature 322 (1986)228-232), presumably because the precursor must unfold to cross the membrane and it cannot do so when complexed with methotrexate. We show here that methotrexate does not block PCDHFR import into chloroplasts. Methotrexate does slow the rate of import, and protects DHFR from degradation once inside chloroplasts. The processed protein is localized in the stroma, indicating that import into thylakoids is impeded. Protease sensitivity assays indicate that the complex of precursor proteinwith methotrexate changes in conformation during the translocation across the envelope.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 31/10/20 alle ore 00:40:46