Neisseria meningitidis Serogroup B Polysialyltransferase: Insights into Substrate Binding
Neisseria meningitidis Serogroup B Polysialyltransferase: Insights into Substrate Binding
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DOI：
10.1002/cbic.200900659
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发表时间：
2010-01-25
期刊：
影响因子：
3.2
通讯作者：
Haselhorst, Thomas
中科院分区：
文献类型：
--
作者：
Boehm, Raphael;Freiberger, Friedrich;Haselhorst, Thomas
脑膜炎奈瑟菌血清群B的聚唾液酸转移酶（NmB-polyST）催化唾液酸（Sia）从活化的唾液酸供体胞苷-5 '单磷酸-N-乙酰神经氨酸（CMP-Neu 5Ac）转移到含唾液酸的受体上，以合成聚唾液酸（polySia）。PolySia构成细胞外囊，是脑膜炎奈瑟菌的一种重要毒力因子。为了更好地理解这种酶如何与其底物相互作用，我们通过饱和转移差（STD）NMR光谱实验确定了与NmB-polyST复合的CMP-Neu 5Ac和三聚体α（2，8）-连接的polySia（DP 3）的结合表位。我们已经发现，供体底物CMP-Neu 5Ac的唾液酸残基与蛋白质的接触比胞嘧啶和核糖部分少。这种与酶的松散结合确保了唾液酸残基快速有效地转移到受体。有趣的是，该酶容纳所有三个唾液酸残基的polySia DP 3受体，但可以观察到一个稍高的饱和转移的N-乙酰基的还原末端唾液酸部分。我们假设，受体底物的内部和非还原性末端唾液酸残基的更开放的结合可以促进合成的聚唾液酸产物的有效释放。还报道了一种基于1D 1H NMR的研究，以监测polySia的生物合成，而不需要荧光或放射性标记的材料。我们的研究首次揭示了这种酶如何与polySia和CMP-Neu 5Ac相互作用的结构信息，促进了新型抗NmB-polyST抑制剂的设计。人类病原体脑膜炎奈瑟菌血清群B（NmB）是发达国家细菌性脑膜炎的主要原因。这种细菌表达的荚膜多糖在化学和免疫学上与宿主生物体中表达的聚唾液酸（polySia）相同。[1]已经表明，与包封的细菌相比，未包封的细菌具有显著降低的抗性水平。[2]这种所谓的抗原模拟和奈瑟氏菌的水合、带负电荷的荚膜规避了调理作用和激活。
The polysialyltransferase from Neisseria meningitidis serogroup B (NmB-polyST) catalyses the transfer of sialic acid (Sia) from activated sialic acid donor cytidine-5’monophosphate-N-acetylneuraminic acid (CMP-Neu5Ac) onto sialic acid containing acceptors to synthesise polysialic acid (polySia). PolySia constitutes the extracellular capsule and is an essential virulence factor for Neisseria meningitidis. To better understand how this enzyme interacts with its substrates, we determined the binding epitope of CMP-Neu5Ac and trimeric α (2, 8)-linked polySia (DP3) in complex with NmB-polyST by means of saturation transfer difference (STD) NMR spectroscopy experiments. We have discovered that the sialic acid residue of the donor substrate CMP-Neu5Ac has fewer contacts with the protein than the cytosine and ribose moieties. This loose binding to the enzyme ensures a fast and efficient transfer of the sialic acid residue to the acceptor. Interestingly, the enzyme accommodates all three sialic acid residues of the polySia DP3 acceptor, but a slightly higher saturation transfer could be observed for the N-acetyl group of the reducing terminal sialic acid moiety. We hypothesise that a more open binding of the internal and nonreducing terminal sialic acid residues of the acceptor substrate may facilitate an efficient release of the synthesised polysialic acid product. A 1D 1H NMR-based investigation to monitor the biosynthesis of polySia without the need of fluorescent or radiolabelled material is also reported. Our study presented here reveals for the first time structural information about how this enzyme interacts with both polySia and CMP-Neu5Ac, facilitating the design of novel anti-NmB-polyST inhibitors.The human pathogen Neisseria meningitidis serogroup B (NmB) is a major cause of bacterial meningitis in developed countries. This bacterium expresses capsular polysaccharides that are chemically and immunologically identical to the polysialic acid (polySia) expressed in the host organism.[1] It has been shown that acapsulated bacteria have a strongly reduced level of resistance compared to encapsulated bacteria.[2] This so-called antigen mimicry and the hydrated, negatively charged capsule of Neisseria circumvent opsonisation and acti-