Betaine lipids overproduced in seed plants are excluded from plastid membranes and promote endomembrane expansion.

Plants and algae have to adapt to environmental changes and face various stresses that negatively affect their growth and development. One common stress is phosphate (Pi) deficiency, which is often present in the environment at limiting levels. In response to Pi deficiency, these organisms increase Pi uptake and remobilize intracellular Pi.

Purification of Chloroplast Envelope, Thylakoids, and Stroma from Angiosperm Leaves.

Plant cell chloroplasts are bounded by a two-membrane envelope. Their photosynthetic function is based on the development of an operational large internal membrane network, called the thylakoids, and on enzymatic processes present in the chloroplast matrix, called the stroma. Thylakoid membranes are distinct from the chloroplast envelope, and their biogenesis is dependent on biosynthetic and transport activities specific of the chloroplast envelope.

PUB11-Dependent Ubiquitination of the Phospholipid Flippase ALA10 Modifies ALA10 Localization and Affects the Pool of Linolenic Phosphatidylcholine.

Biogenesis of photosynthetic membranes depends on galactolipid synthesis, which relies on several cell compartments, notably the endoplasmic reticulum (ER) and the chloroplast envelope. Galactolipid synthesis involves lipid trafficking between both membrane compartments. In , ALA10, a phospholipid flippase of the P type-ATPase family, counteracts the limitation of monogalactosyldiacylglycerol (MGDG) production and has a positive effect on leaf development.

Purification of Chloroplasts and Chloroplast Subfractions: Envelope, Thylakoids, and Stroma-From Spinach, Pea, and Arabidopsis thaliana.

Chloroplasts are specific organelles of plant cells dedicated to photosynthesis and delimited by a two-membrane chloroplast envelope. Their photosynthetic function is based on the development of an operational large internal membrane network, called the thylakoids, and on enzymatic processes present in the chloroplast matrix, called the stroma. Thylakoid membranes are clearly different from the chloroplast envelope and their biogenesis is dependent on biosynthetic and transport activities specific of the chloroplast envelope.

Levels of polyunsaturated fatty acids correlate with growth rate in plant cell cultures.

In higher plants, fatty acids (FAs) with 18 carbons (18C) represent about 70% of total FAs, the most abundant species being 18:2 and 18:3. These two polyunsaturated FAs (PUFAs) represent about 55% of total FAs in Arabidopsis cell suspension cultures, whereas 18:1 represents about 10%. The level of PUFAs may vary, depending on ill-defined factors.

The selective biotin tagging and thermolysin proteolysis of chloroplast outer envelope proteins reveals information on protein topology and association into complexes.

The understanding of chloroplast function requires the precise localization of proteins in each of its sub-compartments. High-sensitivity mass spectrometry has allowed the inventory of proteins in thylakoid, stroma, and envelope fractions. Concerning membrane association, proteins can be either integral or peripheral or even soluble proteins bound transiently to a membrane complex.

C1 metabolism and chlorophyll synthesis: the Mg-protoporphyrin IX methyltransferase activity is dependent on the folate status.

* Tetrahydrofolate derivatives are central cofactors of C1 metabolism. Using methotrexate as a specific inhibitor of folate biosynthesis, we altered the folate status in 10-d-old etiolated pea (Pisum sativum) leaves and followed the rate of chlorophyll synthesis upon illumination. * In our conditions, the folate concentration decreased only from 5.

Phosphate availability affects the tonoplast localization of PLDzeta2, an Arabidopsis thaliana phospholipase D.

Under phosphate deprivation, higher plants change their lipid composition and recycle phosphate from phospholipids. A phospholipase D, PLDzeta2, is involved in this recycling and in other cellular functions related to plant development. We investigated the localization of Arabidopsis PLDzeta2 by cell fractionation and in vivo GFP confocal imaging.

Knock-out of the magnesium protoporphyrin IX methyltransferase gene in Arabidopsis. Effects on chloroplast development and on chloroplast-to-nucleus signaling.

Protoporphyrin IX is the last common intermediate between the heme and chlorophyll biosynthesis pathways. The addition of magnesium directs this molecule toward chlorophyll biosynthesis. The first step downstream from the branchpoint is catalyzed by the magnesium chelatase and is a highly regulated process.

Arabidopsis CHL27, located in both envelope and thylakoid membranes, is required for the synthesis of protochlorophyllide.

CHL27, the Arabidopsis homologue to Chlamydomonas Crd1, a plastid-localized putative diiron protein, is required for the synthesis of protochlorophyllide and therefore is a candidate subunit of the aerobic cyclase in chlorophyll biosynthesis. delta-Aminolevulinic acid-fed antisense Arabidopsis plants with reduced amounts of Crd1/CHL27 accumulate Mg-protoporphyrin IX monomethyl ester, the substrate of the cyclase reaction. Mutant plants have chlorotic leaves with reduced abundance of all chlorophyll proteins.

The plant S-adenosyl-L-methionine:Mg-protoporphyrin IX methyltransferase is located in both envelope and thylakoid chloroplast membranes.

Chlorophyll biosynthesis requires a metabolic dialog between the chloroplast envelope and thylakoids where biosynthetic activities are localized. Here, we report the first plant S-adenosyl-l-methionine:Mg-protoporphyrin IX methyltransferase (MgP(IX)MT) sequence identified in the Arabidopsis genome owing to its similarity with the Synechocystis sp. MgP(IX)MT gene.