Transfer of palmitate from phospholipids to lipid A in outer membranes of Gram-negative bacteria
AUTOR(ES)
Bishop, Russell E.
FONTE
Oxford University Press
RESUMO
Regulated covalent modifications of lipid A are implicated in virulence of pathogenic Gram-negative bacteria. The Salmonella typhimurium PhoP/PhoQ-activated gene pagP is required both for biosynthesis of hepta-acylated lipid A species containing palmitate and for resistance to cationic anti-microbial peptides. Palmitoylated lipid A can also function as an endotoxin antagonist. We now show that pagP and its Escherichia coli homolog (crcA) encode an unusual enzyme of lipid A biosynthesis localized in the outer membrane. PagP transfers a palmitate residue from the sn-1 position of a phospholipid to the N-linked hydroxymyristate on the proximal unit of lipid A (or its precursors). PagP bearing a C-terminal His6-tag accumulated in outer membranes during overproduction, was purified with full activity and was shown by cross-linking to behave as a homodimer. PagP is the first example of an outer membrane enzyme involved in lipid A biosynthesis. Additional pagP homologs are encoded in the genomes of Yersinia and Bordetella species. PagP may provide an adaptive response toward both Mg2+ limitation and host innate immune defenses.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=302101Documentos Relacionados
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