Sinorhizobium meliloti phospholipase C required for lipid remodeling during phosphorus limitation.
Proc Natl Acad Sci U S A
; 107(1): 302-7, 2010 Jan 05.
Article
em En
| MEDLINE
| ID: mdl-20018679
ABSTRACT
Rhizobia are Gram-negative soil bacteria able to establish nitrogen-fixing root nodules with their respective legume host plants. Besides phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine, rhizobial membranes contain phosphatidylcholine (PC) as a major membrane lipid. Under phosphate-limiting conditions of growth, some bacteria replace their membrane phospholipids with lipids lacking phosphorus. In Sinorhizobium meliloti, these phosphorus-free lipids are sulfoquinovosyl diacylglycerol, ornithine-containing lipid, and diacylglyceryl trimethylhomoserine (DGTS). Pulse-chase experiments suggest that the zwitterionic phospholipids phosphatidylethanolamine and PC act as biosynthetic precursors of DGTS under phosphorus-limiting conditions. A S. meliloti mutant, deficient in the predicted phosphatase SMc00171 was unable to degrade PC or to form DGTS in a similar way as the wild type. Cell-free extracts of Escherichia coli, in which SMc00171 had been expressed, convert PC to phosphocholine and diacylglycerol, showing that SMc00171 functions as a phospholipase C. Diacylglycerol , in turn, is the lipid anchor from which biosynthesis is initiated during the formation of the phosphorus-free membrane lipid DGTS. Inorganic phosphate can be liberated from phosphocholine. These data suggest that, in S. meliloti under phosphate-limiting conditions, membrane phospholipids provide a pool for metabolizable inorganic phosphate, which can be used for the synthesis of other essential phosphorus-containing biomolecules. This is an example of an intracellular phospholipase C in a bacterial system; however, the ability to degrade endogenous preexisting membrane phospholipids as a source of phosphorus may be a general property of Gram-negative soil bacteria.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Fosfolipases Tipo C
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Fósforo
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Proteínas de Bactérias
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Sinorhizobium meliloti
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Lipídeos de Membrana
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
México