Translocation of the potato 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase into isolated spinach chloroplasts
- Purdue Univ., West Lafayette, IN (USA)
A cDNA for potato (Solanum tuberosum L.) 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, the first enzyme of the shikimate pathway, encodes a 56 KD polypeptide whose amino terminus resembles a chloroplast transit sequence. The cDNA was placed downstream of the phage T7 polymerase recognition sequence in plasmid pGEM-3Z. DNA of the resulting plasmid pGEM-DWZ directed T7 polymerase to synthesize potato DAHP synthase mRNA in vitro. The mRNA was used in wheat germ and rabbit reticulocyte lysates for the synthesis of {sup 35}S-labeled pro-DAHP synthase. The predominant translation product is a 59 KD polypeptide that can be immunoprecipitated by rabbit polyclonal antibodies raised against the 53 KD DAHP synthase purified from potato tubers. Isolated spinach chloroplasts process the 59 KD pro-DAHP synthase to a 50 KD polypeptide. The processed polypeptide is protected from protease degradation, suggesting uptake of the enzyme into the cell organelle. Fractionation of reisolated chloroplasts after import of pro-DAHP synthase showed mature enzyme in the stroma. The uptake and processing of DAHP synthase is inhibited by antibodies raised against the mature enzyme. Our results are consistent with the assumption that potato contains a nuclear DNA encoded DAHP synthase that is synthesized as a proenzyme and whose mature form resides in the chloroplasts. Our data provide further evidence that green plants synthesize aromatic amino acids in plastids.
- OSTI ID:
- 5841322
- Report Number(s):
- CONF-9007196--
- Journal Information:
- Plant Physiology, Supplement; (USA), Journal Name: Plant Physiology, Supplement; (USA) Vol. 93:1; ISSN PPYSA; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOSYNTHESIS
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
DNA
EVEN-ODD NUCLEI
FOOD
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MESSENGER-RNA
NUCLEI
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLANTS
RADIOISOTOPES
RNA
SOLANUM
SOLANUM TUBEROSUM
SPINACH
SULFUR 35
SULFUR COMPOUNDS
SULFUR ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
VEGETABLES