Identification of a lipopolysaccharide α-2,3-sialyltransferase from Haemophilus influenzae
Identification of a lipopolysaccharide α-2,3-sialyltransferase from Haemophilus influenzae
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DOI：
10.1046/j.1365-2958.2001.02204.x
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发表时间：
2001-01-01
影响因子：
3.6
通讯作者：
Wakarchuk, WW
中科院分区：
文献类型：
--
作者：
Hood, DW;Cox, AD;Wakarchuk, WW
我们已经鉴定了一个基因，该基因用于将N-乙酰神经氨酸（Neu 5Ac）添加到人病原体流感嗜血杆菌的脂多糖（LPS）的乳糖基受体部分的α-2，3-键中。该基因是先前被鉴定为称为lic 3A的相位可变基因的基因。H.在使用具有末端半乳糖基、乳糖基或N-乙酰基-乳糖胺基部分的合成荧光受体的测定中，流感病毒以及产生Lic 3A的重组大肠杆菌菌株证明了唾液酸转移酶活性。RM 118株H.在流感病毒中，Lic 3A活性通过另一种相可变糖基转移酶LgtC的作用调节，LgtC竞争相同的乳糖基受体部分。使用质谱法和核磁共振（NMR）光谱法对来自RM 118：IgtC突变体和不可分型菌株486的LPS进行结构分析，证实主要唾液酸化物质具有远离远端庚糖的唾液酸-α-（2-3）-乳糖基延伸。这种唾液酸化的糖型在含有lic 3A基因破坏的菌株中不存在。RM 118：lgtC lic 3A中存在少量唾液酸化的较高分子量糖型，表明存在第二种唾液酸转移酶。Lic 3A突变体。流感病毒株对正常人血清的杀伤作用显示出降低的抗性。Lic 3A是第一个报道的具有α-2，3-唾液酸转移酶活性的相位可变的唾液酸转移酶基因。
We have identified a gene for the addition of N-acetylneuraminic acid (Neu5Ac) in an alpha -2,3-linkage to a lactosyl acceptor moiety of the lipopolysaccharide (LPS) of the human pathogen Haemophilus influenzae. The gene is one that was identified previously as a phase-variable gene known as lic3A. Extracts of H. influenzae, as well as recombinant Escherichia coli strains producing Lic3A, demonstrate sialyltransferase activity in assays using synthetic fluorescent acceptors with a terminal galactosyl, lactosyl or N-acetyl-lactosaminyl moiety. In the RM118 strain of H. influenzae, Lic3A activity is modulated by the action of another phase-variable glycosyltransferase, LgtC, which competes for the same lactosyl acceptor moiety. Structural analysis of LPS from a RM118:lgtC mutant and the non-typeable strain 486 using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy confirmed that the major sialylated species has a sialyl-alpha-(2-3)-lactosyl extension off the distal heptose. This sialylated glycoform was absent in strains containing a lic3A gene disruption. Low amounts of sialylated higher molecular mass glycoforms were present in RM118:lgtC lic3A, indicating the presence of a second sialyltransferase. Lic3A mutants of H. influenzae strains show reduced resistance to the killing effects of normal human serum. Lic3A, encoding an alpha -2,3-sialyltransferase activity, is the first reported phase-variable sialyltransferase gene.