scholarly journals Synthesis of Long-Chain Acyl-CoA in Chloroplast Envelope Membranes

1981 ◽  
Vol 67 (2) ◽  
pp. 250-256 ◽  
Author(s):  
Jacques Joyard ◽  
Paul K. Stumpf
2000 ◽  
Vol 78 (3) ◽  
pp. 328-335 ◽  
Author(s):  
Christine Masterson ◽  
Clifford Wood

Carnitine palmitoyltransferase (EC 2.3.1.21), an enzyme that catalyses the reversible transfer of activated long-chain acyl groups between CoASH and L-carnitine, has been confirmed in pea leaf chloroplasts. This enzyme is bound to the chloroplast inner envelope membrane and has two isoforms, one bound to the outside (cytosol side) of the inner envelope and one bound to the inside (stromal side) of the inner envelope. Malonyl CoA inhibited the activity of the outer carnitine palmitoyltransferase, while stimulating the activity of the inner isoform and may be a regulator of these enzymes in vivo. Carnitine palmitoyltransferase was solubilized from the chloroplast envelope by detergent treatment and the two isoforms separated by Q-Sepharose anion exchange chromatography. Both proteins were immunochemically observed by probing Western blots of sodium dodecyl sulfate - polyacrylamide gel electrophoresis gels using an anti-beef heart mitochondrial carnitine palmitoyltransferase polyclonal antibody. The monomeric molecular mass of the protein recognized by this antibody was approximately 20 kDa. This 20-kDa protein also bound3H-carnitine. Both isoforms had broad acyl CoA substrate specificities, but showed increased activity with desaturated long-chain acyl CoAs, exhibiting a preference for linolenoyl CoA. A role for carnitine palmitoyltransferase in the shuttling of fatty acids across the chloroplast envelope is suggested.Key words: Pisum sativum, chloroplasts, carnitine palmitoyltransferase, fatty acid metabolism, eukaryotic pathway, membrane transport.


2020 ◽  
Vol 21 (6) ◽  
pp. 2223
Author(s):  
Aya Kitajima-Koga ◽  
Marouane Baslam ◽  
Yuuki Hamada ◽  
Namiko Ito ◽  
Tomoko Taniuchi ◽  
...  

The long-chain acyl-CoA synthetases (LACSs) are involved in lipid synthesis, fatty acid catabolism, and the transport of fatty acids between subcellular compartments. These enzymes catalyze the critical reaction of fatty acyl chains to fatty acyl-CoAs for the triacylglycerol biosynthesis used as carbon and energy reserves. In Arabidopsis, LACSs are encoded by a family of nine genes, with LACS9 being the only member located in the chloroplast envelope membrane. However, the comprehensive role of LACS9 and its contribution to plant metabolism have not been explored thoroughly. In this study, we report on the identification and characterization of LACS9 mutants in rice plants. Our results indicate that the loss-of-function mutations in OsLACS9 affect the architecture of internodes resulting in dwarf plants with large starch granules in the chloroplast, showing the suppression of starch degradation. Moreover, the plastid localization of α-amylase I-1 (AmyI-1)—a key enzyme involved in starch breakdown in plastids—was suppressed in the lacs9 mutant line. Immunological and confocal laser scanning microscopy analyses showed that OsLACS9-GFP is located in the chloroplast envelope in green tissue. Microscopic analysis showed that OsLACS9s interact with each other in the plastid envelope membrane. Furthermore, OsLACS9 is also one of the proteins transported to plastids without a transit peptide or involvement of the Toc/Tic complex system. To identify the plastid-targeting signal of OsLACS9, the transient expression and localization of a series of N-terminal truncated OsLACS9-green fluorescent protein (GFP) fusion proteins were examined. Truncation analyses identified the N-terminal 30 amino acid residues to be required for OsLACS9 plastid localization. Overall, the data in this study provide an advanced understanding of the function of OsLACS9 and its role in starch degradation and plant growth.


1991 ◽  
Vol 266 (7) ◽  
pp. 4214-4219
Author(s):  
H Tomoda ◽  
K Igarashi ◽  
J C Cyong ◽  
S Omura

2021 ◽  
Vol 27 ◽  
pp. 100749
Author(s):  
Eugène F. Diekman ◽  
Michel van Weeghel ◽  
Mayte Suárez-Fariñas ◽  
Carmen Argmann ◽  
Pablo Ranea-Robles ◽  
...  

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