Crystal structures of Wzb of Escherichia coli and CpsB of Streptococcus pneumoniae, representatives of two families of tyrosine phosphatases that regulate capsule assembly.
Crystal structures of Wzb of Escherichia coli and CpsB of Streptococcus pneumoniae, representatives of two families of tyrosine phosphatases that regulate capsule assembly.
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DOI：
10.1016/j.jmb.2009.07.026
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发表时间：
2009-09-25
影响因子：
5.6
通讯作者：
Naismith, James H.
中科院分区：
文献类型：
--
作者：
Hagelueken, Gregor;Huang, Hexian;Mainprize, Iain L.;Whitfield, Chris;Naismith, James H.
许多革兰氏阳性和革兰氏阴性细菌利用称为胶囊的多糖表面层来逃避免疫系统;因此，胶囊的合成和输出是潜在的治疗靶点。在大肠杆菌K-30中，整合的膜酪氨酸自激酶Wzc和同源磷酸酶Wzb已被证明是合成和组装荚膜多糖的关键。在革兰氏阳性细菌肺炎链球菌中，CpsCD复合物类似于Wzc，磷酸酶CpsB是相应的同源磷酸酶。已知磷酸酶使其相应的自激酶去磷酸化，然而尽管它们的功能等同，但它们没有序列同源性。我们目前的结构WZB与磷酸盐和高分辨率结构的apo-CpsB和磷酸盐络合的CpsB复合。我们表明，这两种蛋白质都对Wzc有活性，从而证明CpsB对CpsCD没有特异性。CpsB是一种新的酶，代表了来自革兰氏阳性细菌的酪氨酸磷酸酶的第一个解决的结构。WZB和CpsB具有完全不同的结构，这表明它们必须通过非常不同的机制运行。虽然Wzb的机制可以从以前的研究中推断出来，但CpsB似乎具有以前未观察到的酪氨酸磷酸酶机制。我们提出了一个化学机制CpsB的基础上定点突变和结构数据。
Many Gram-positive and Gram-negative bacteria utilize polysaccharide surface layers called capsules to evade the immune system; consequently, the synthesis and export of the capsule are a potential therapeutic target. In Escherichia coli K-30, the integral membrane tyrosine autokinase Wzc and the cognate phosphatase Wzb have been shown to be key for both synthesis and assembly of capsular polysaccharides. In the Gram-positive bacterium Streptococcus pneumoniae, the CpsCD complex is analogous to Wzc and the phosphatase CpsB is the corresponding cognate phosphatase. The phosphatases are known to dephosphorylate their corresponding autokinases, yet despite their functional equivalence, they share no sequence homology. We present the structure of Wzb in complex with phosphate and high-resolution structures of apo-CpsB and a phosphate-complexed CpsB. We show that both proteins are active toward Wzc and thereby demonstrate that CpsB is not specific for CpsCD. CpsB is a novel enzyme and represents the first solved structure of a tyrosine phosphatase from a Gram-positive bacterium. Wzb and CpsB have completely different structures, suggesting that they must operate by very different mechanisms. Although the mechanism of Wzb can be inferred from previous studies, CpsB appears to have a tyrosine phosphatase mechanism not observed before. We propose a chemical mechanism for CpsB based on site-directed mutagenesis and structural data.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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作者：
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通讯作者：
Gilbert, Christophe
影响因子：
14.9
作者：
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通讯作者：
Richardson DC