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Solution NMR structure of the outer membrane enzyme PagP in OG micellesSolution NMR structure of the outer membrane enzyme PagP in OG micelles
Structural highlights
FunctionPAGP_ECOLI PagP is required both for biosynthesis of hepta-acylated lipid A species containing palmitate and for resistance to cationic antimicrobial peptides (CAMPs). It catalyzes the transfer of a palmitate chain (16:0) from the sn-1 position of a glycerophospholipid to the free hydroxyl group of the (R)-3-hydroxymyristate chain at position 2 of lipid A (endotoxin). Modifications of lipid A with a palmitate chain allow to evade host immune defenses by resisting antimicrobial peptides and attenuating the inflammatory response to infection triggered by lipopolysaccharide through the Toll-like receptor 4 (TLR4) signal transduction pathway. Phosphatidylglycerol (PtdGro), phosphatidylethanolamine (PtdEtn), phosphatidylserine (PtdSer) and phosphatidic acid (Ptd-OH) are all effective acyl donors.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe bacterial outer membrane enzyme PagP transfers a palmitate chain from a phospholipid to lipid A. In a number of pathogenic Gram-negative bacteria, PagP confers resistance to certain cationic antimicrobial peptides produced during the host innate immune response. The global fold of Escherichia coli PagP was determined in both dodecylphosphocholine and n-octyl-beta-d-glucoside detergent micelles using solution NMR spectroscopy. PagP consists of an eight-stranded anti-parallel beta-barrel preceded by an amphipathic alpha helix. The beta-barrel is well defined, whereas NMR relaxation measurements reveal considerable mobility in the loops connecting individual beta-strands. Three amino acid residues critical for enzymatic activity localize to extracellular loops near the membrane interface, positioning them optimally to interact with the polar headgroups of lipid A. Hence, the active site of PagP is situated on the outer surface of the outer membrane. Because the phospholipids that donate palmitate in the enzymatic reaction are normally found only in the inner leaflet of the outer membrane, PagP activity may depend on the aberrant migration of phospholipids into the outer leaflet. This finding is consistent with an emerging paradigm for outer membrane enzymes in providing an adaptive response toward disturbances in the outer membrane. Solution structure and dynamics of the outer membrane enzyme PagP by NMR.,Hwang PM, Choy WY, Lo EI, Chen L, Forman-Kay JD, Raetz CR, Prive GG, Bishop RE, Kay LE Proc Natl Acad Sci U S A. 2002 Oct 15;99(21):13560-5. Epub 2002 Sep 30. PMID:12357033[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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