Linked Life Data

15024005

Source:http://linkedlifedata.com/resource/pubmed/id/15024005

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
2004-5-17
pubmed:databankReference
pubmed:abstractText
The subcellular distribution of Met and S-adenosylmethionine (AdoMet) metabolism in plant cells discloses a complex partition between the cytosol and the organelles. In the present work we show that Arabidopsis contains three functional isoforms of vitamin B(12)-independent methionine synthase (MS), the enzyme that catalyzes the methylation of homocysteine to Met with 5-methyltetrahydrofolate as methyl group donor. One MS isoform is present in chloroplasts and is most likely required to methylate homocysteine that is synthesized de novo in this compartment. Thus, chloroplasts are autonomous and are the unique site for de novo Met synthesis in plant cells. The additional MS isoforms are present in the cytosol and are most probably involved in the regeneration of Met from homocysteine produced in the course of the activated methyl cycle. Although Met synthesis can occur in chloroplasts, there is no evidence that AdoMet is synthesized anywhere but the cytosol. In accordance with this proposal, we show that AdoMet is transported into chloroplasts by a carrier-mediated facilitated diffusion process. This carrier is able to catalyze the uniport uptake of AdoMet into chloroplasts as well as the exchange between cytosolic AdoMet and chloroplastic AdoMet or S-adenosylhomocysteine. The obvious function for the carrier is to sustain methylation reactions and other AdoMet-dependent functions in chloroplasts and probably to remove S-adenosylhomocysteine generated in the stroma by methyltransferase activities. Therefore, the chloroplastic AdoMet carrier serves as a link between cytosolic and chloroplastic one-carbon metabolism.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
22548-57
pubmed:dateRevised
2004-12-15
pubmed:meshHeading
pubmed-meshheading:15024005-Arabidopsis, pubmed-meshheading:15024005-Blotting, Western, pubmed-meshheading:15024005-Chloroplasts, pubmed-meshheading:15024005-Cloning, Molecular, pubmed-meshheading:15024005-Cytosol, pubmed-meshheading:15024005-DNA, Complementary, pubmed-meshheading:15024005-Diffusion, pubmed-meshheading:15024005-Dose-Response Relationship, Drug, pubmed-meshheading:15024005-Escherichia coli, pubmed-meshheading:15024005-Green Fluorescent Proteins, pubmed-meshheading:15024005-Homocysteine, pubmed-meshheading:15024005-Immunoblotting, pubmed-meshheading:15024005-Kinetics, pubmed-meshheading:15024005-Luminescent Proteins, pubmed-meshheading:15024005-Methionine, pubmed-meshheading:15024005-Mitochondria, pubmed-meshheading:15024005-Models, Biological, pubmed-meshheading:15024005-Molecular Sequence Data, pubmed-meshheading:15024005-Peas, pubmed-meshheading:15024005-Phylogeny, pubmed-meshheading:15024005-Plastids, pubmed-meshheading:15024005-Protein Isoforms, pubmed-meshheading:15024005-S-Adenosylmethionine, pubmed-meshheading:15024005-Time Factors, pubmed-meshheading:15024005-Vitamin B 12
pubmed:year
2004
pubmed:articleTitle
Methionine metabolism in plants: chloroplasts are autonomous for de novo methionine synthesis and can import S-adenosylmethionine from the cytosol.
pubmed:affiliation
Département de Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 Rue des Martyrs, 38054 Grenoble Cedex 9, France. sravane1@cea.fr
pubmed:publicationType
Journal Article