Ca2+-induced phosphoethanolamine transfer to the outer 3-deoxy-D-manno-octulosonic acid moiety of Escherichia coli lipopolysaccharide -: A novel membrane enzyme dependent upon phosphatidylethanolamine
Ca2+-induced phosphoethanolamine transfer to the outer 3-deoxy-D-manno-octulosonic acid moiety of Escherichia coli lipopolysaccharide -: A novel membrane enzyme dependent upon phosphatidylethanolamine
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DOI：
10.1074/jbc.m009019200
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发表时间：
2001-01-12
影响因子：
4.8
通讯作者：
Raetz, CRH
中科院分区：
文献类型：
--
作者：
Kanipes, MI;Lin, SH;Raetz, CRH
大肠杆菌和沙门氏菌的某些菌株含有在3-脱氧-d -甘露-辛糖酸（Kdo）残基的第7位被磷酸乙醇胺（pEtN）基团修饰的脂多糖（LPS）。利用缺肝素E，大肠杆菌突变体WBB06 (Brabetz， W, Muller-Loennies， S., Hoist， O, and Brade， H. (1997)；J. Biochem. 247, 716-724)，我们现在证明了决定pEtN存在与否的关键参数是介质中CaCl2的浓度。质谱分析表明，在添加5 mM CaCl2的营养液中生长的WBB06中，有一半的LPS被pEtN衍生，而在不添加CaCl2的情况下生长的WBB06的LPS则没有衍生。大肠杆菌WBB06或野生型W3110在5-50 mM CaCl2上生长的膜含有一种新的pEtN转移酶，该酶使用前体Kdo(2)-[4'- p -32]脂质IVA作为受体。5-50 mM CaCl2对pEtN转移酶的诱导表明可能在建立转化能力或抵抗环境胁迫中起作用，并且代表了大肠杆菌LPS内核受调控的共价修饰的第一个例子。
Certain strains of Escherichia coli and Salmonella contain lipopolysaccharide (LPS) modified with a phosphoethanolamine (pEtN) group at position 7 of the outer 3-deoxy-D-manno-octulosonic acid (Kdo) residue. Using the heptose-deficient E, coli mutant WBB06 (Brabetz, W,, Muller-Loennies, S., Hoist, O, and Brade, H. (1997) Eur. J. Biochem. 247, 716-724), we now demonstrate that the critical parameter determining the presence or absence of pEtN is the concentration of CaCl2 in the medium. As judged by mass spectrometry, half the LPS in WBB06, grown on nutrient broth with 5 mM CaCl2, is derivatized with a pEtN group, whereas LPS from WBB06 grown without supplemental CaCl2 is not. Membranes from E, coli WBB06 or wild-type W3110 grown on 5-50 mM CaCl2 contain a novel pEtN transferase that uses the precursor Kdo(2)-[4'-P-32]lipid IVA as an acceptor. Transferase is not present in membranes of E. coli grown with 5 mM MgCl2, BaCl2, or ZnCl2, Hydrolysis of the in vitro reaction product, pEtN-Kdo(2)-[4'-P-32]lipid IVA, at pH 4.5 shows that the pEtN substituent is located on the outer Kdo moiety, Membranes from an E, coli pss knockout mutant grown on 50 mM CaCl2, which lack phosphatidylethanolamine, do not contain measurable transferase activity unless exogenous phosphatidylethanolamine is added back to the assay system. The induction of the pEtN transferase by 5-50 mM CaCl2 suggests possible role(s) in establishing transformation competence or resisting environmental stress, and represents the first example of a regulated covalent modification of the inner core of E. coli LPS.