Metabolic pathways of the wheat (Triticum aestivum) endosperm amyloplast revealed by proteomics.
BACKGROUND
By definition, amyloplasts are plastids specialized for starch production. However, a proteomic study of amyloplasts isolated from wheat (Triticum aestivum Butte 86) endosperm at 10 days after anthesis (DPA) detected enzymes from many other metabolic and biosynthetic pathways. To better understand the role of amyloplasts in food production, the data from that study were evaluated in detail and an amyloplast metabolic map was outlined.


RESULTS
Analysis of 288 proteins detected in an amyloplast preparation predicted that 178 were amyloplast proteins. Criteria included homology with known plastid proteins, prediction of a plastid transit peptide for the wheat gene product or a close homolog, known plastid location of the pathway, and predicted plastid location for other members of the same pathway. Of these, 135 enzymes were arranged into 18 pathways for carbohydrate, lipid, amino acid, nucleic acid and other biosynthetic processes that are critical for grain-fill. Functions of the other proteins are also discussed.


CONCLUSIONS
The pathways outlined in this paper suggest that amyloplasts play a central role in endosperm metabolism. The interacting effects of genetics and environment on starch and protein production may be mediated in part by regulatory mechanisms within this organelle.
Dupont
Frances M
FM
Western Regional Research Center, United States Department of Agriculture, Agricultural Research Service, 800 Buchanan Street, Albany, CA 94710K, USA. frances.dupont@ars.usda.gov
D000596:Amino Acids / Q000096:biosynthesis; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D005227:Fatty Acids / Q000096:biosynthesis; D053858:Metabolic Networks and Pathways; D024101:Mitochondrial Proteins / Q000378:metabolism; D009696:Nucleic Acids / Q000096:biosynthesis; D010084:Oxidation-Reduction; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010940:Plant Proteins / Q000145:classification / Q000378:metabolism; D018087:Plastids / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism; D014176:Protein Biosynthesis; D040901:Proteomics; D012639:Seeds / Q000378:metabolism*; D015398:Signal Transduction; D020524:Thylakoids / Q000378:metabolism; D014908:Triticum / Q000166:cytology* / Q000378:metabolism*; D014815:Vitamins / Q000378:metabolism
D000596:Amino Acids; D005227:Fatty Acids; D024101:Mitochondrial Proteins; D009696:Nucleic Acids; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011166:Porphyrins; D014815:Vitamins