Chloroplast Biogenesis. Regulation of Lipid Transport to the Thylakoid in Chloroplasts Isolated from Expanding and Fully Expanded Leaves of Pea

Abstract

To study the regulation of lipid transport from the chloroplast envelope to the thylakoid, intact chloroplasts, isolated from fully expanded or still-expanding pea (Pisum sativum) leaves, were incubated with radiolabeled lipid precursors and thylakoid membranes subsequently were isolated. Incubation with UDP[ 3 H]Gal labeled monogalactosyldiacylglycerol in both envelope membranes and digalactosyldiacylglycerol in the outer chloroplast envelope. Galactolipid synthesis increased with incubation temperature. Transport to the thylakoid was slow below 12°C, and exhibited a temperature dependency closely resembling that for the previously reported appearance and disappearance of vesicles in the stroma (D.J. Morré, G. Selldén, C. Sundqvist, A.S. Sandelius [1991] Plant Physiol 97: 1558-1564). In mature chloroplasts, monogalactosyldiacylglycerol transport to the thylakoid was up to three times higher than digalactosyldiacylglycerol transport, whereas the difference was markedly lower in developing chloroplasts. Incubation of chloroplasts with [ 14 C]acyl-coenzyme A labeled phosphatidylcholine (PC) and free fatty acids in the inner envelope membrane and phosphatidylglycerol at the chloroplast surface. PC and phosphatidylglycerol were preferentially transported to the thylakoid. Analysis of lipid composition revealed that the thylakoid contained approximately 20% of the chloroplast PC. Our results demonstrate that lipids synthesized at the chloroplast surface as well as in the inner envelope membrane are transported to the thylakoid and that lipid sorting is involved in the process. Furthermore, the results also indicate that more than one pathway exists for galactolipid transfer from the chloroplast envelope to the thylakoid.

The K-Segment of Maize DHN1 Mediates Binding to Anionic Phospholipid Vesicles and Concomitant Structural Changes

“…Particularly in the transport of lipid to the thylakoid in chloroplasts of plants adapted to low temperature, vesicles accumulate in the stroma. It has been proposed that vesicle fusion is blocked at low temperature (Andersson et al, 2001). In addition, vesicles involved in membrane trafficking of the plasma membrane are very rich in anionic phospholipids such as PA and phosphatidylserine (Liscovitch and Cantley, 1995).…”

A chloroplast-localized vesicular transport system: a bio-informatics approach

“…Morphological [5,9,28], and biochemical evidence [4,7,8] suggest that lipid transport from the chloroplast envelope to the thylakoid membrane is mediated by a vesicular transport mechanism. The bio-informatics data presented herein suggest that homologues of the components required for formation of COPII coated vesicles are present in the chloroplasts of higher plants.…”

“…Newly synthesized lipids are rapidly transported from the chloroplast envelope to the thylakoid membrane [1-4]. In theory, lipid transport across the aqeous stroma could be mediated by lipid transfer at sites of physical contact between the envelope and the thylakoid, by monomer diffusion facilitated by lipid transfer proteins or by a vesicular mechanism.…”

“…The low temperature-dependent accumulation of vesicles is considered to reflect that fusion of vesicles with the target membrane (in the examples above thylakoid and cis -Golgi, respectively) is blocked at a higher temperature than vesicle fission from the donor membrane (chloroplast envelope and ER, respectively) [5]. It was subsequently shown that the transfer of lipids from envelope to thylakoid in organello was strongly inhibited at the temperatures where vesicles accumulated in the stroma [4]. A cell-free reconstitution of lipid transport from envelope to thylakoid demonstrated a requirement for stromal proteins and ATP [7] and the release of lipids from isolated envelope required stromal proteins, ATP and GTP and was stimulated by acyl-CoA [8].…”

Genes co-expressed with CPSAR1 identified using ATTED-II

“…[1][2][3][4] Transport of nonproteinaceous material, such as lipids, to the thylakoid has not been studied to the same extent, although several reports do exist. [5][6][7][8] Since thylakoids do not produce lipids themselves any lipids present must have been transported from the production site, i.e., the envelope. 9,10 Experimental data support the theory of a vesicular transport system and it has been predicted that several proteins resembling those important in the cytosolic vesicle transport system are chloroplast localized.…”