Lipid mobilization and gluconeogenesis in plants: Do glyoxylate cycle enzyme activities constitute a real cycle? A hypothesis

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Version: Final published version
Serval ID
serval:BIB_77AC1742D3BA
Type
Article: article from journal or magazin.
Publication sub-type
Review (review): journal as complete as possible of one specific subject, written based on exhaustive analyses from published work.
Collection
Publications
Title
Lipid mobilization and gluconeogenesis in plants: Do glyoxylate cycle enzyme activities constitute a real cycle? A hypothesis
Journal
Biological Chemistry
Author(s)
Escher C.L., Widmer F.
ISSN
1431-6730
Publication state
Published
Issued date
1997
Peer-reviewed
Oui
Volume
378
Number
8
Pages
803-813
Language
english
Abstract
Glyoxysomes are specialized peroxisomes present in various plant organs such as germinating cotyledons or senescing leaves. They are the site of beta-oxidation and of the glyoxylate cycle. These consecutive pathways are essential to the maintenance of gluconeogenesis initiated by the degradation of reserve or structural lipids.
In contrast to mitochondrial beta-oxidation, which is prevalent in animal cells, glyoxysomal beta-oxidation and the glyoxylate cycle have no direct access to the mitochondrial respiratory chain because of the impermeability of the glyoxysomal membrane to the reduced cofactors. The necessity of NAD(+) regeneration can conceivably be fulfilled by membrane redox chains and/or by transmembrane shuttles.
Experimental evidence based on the active metabolic roles of higher plant glyoxysomes and yeast peroxisomes suggests the coexistence of two mechanisms, namely a reductase/peroxidase membrane redox chain and a malate/aspartate shuttle susceptible to transfer electrons to the mitochondrial ATP generating system.
Such a model interconnects beta-oxidation, the glyoxylate cycle, the respiratory chain and gluconeogenesis in such a way that glyoxysomal malate dehydrogenase is an essential and exclusive component of beta-oxidation (NAD(+) regeneration). Consequently, the classical view of the glyoxylate cycle is superseded by a tentative reactional scheme deprived of cyclic character.
Keywords
beta-oxidation, gluconeogenesis, glyoxylate cycle, glyoxysomes, lipids, peroxisomes, CASTOR-BEAN ENDOSPERM, ACID BETA-OXIDATION, SPINACH LEAF PEROXISOMES, SENESCENT BARLEY LEAVES, MALATE SYNTHASE, GLYOXYSOMAL MEMBRANES, ELECTRON-TRANSPORT, ENDOPLASMIC-RETICULUM, PUMPKIN COTYLEDONS, ASCORBATE PEROXIDASE
Pubmed
Web of science
Create date
13/08/2015 8:54
Last modification date
20/08/2019 15:34
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