Structure of the type III pantothenate kinase from Bacillus anthracis at 2.0 Å resolution:: Implications for coenzyme A-dependent redox biology
Structure of the type III pantothenate kinase from Bacillus anthracis at 2.0 Å resolution:: Implications for coenzyme A-dependent redox biology
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DOI：
10.1021/bi062299p
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发表时间：
2007-03-20
期刊：
影响因子：
2.9
通讯作者：
Claiborne, Al
中科院分区：
文献类型：
--
作者：
Nicely, Nathan I.;Parsonage, Derek;Claiborne, Al
辅酶A （CoASH）是金黄色葡萄球菌和许多其他细菌中主要的低分子量硫醇；最近有报道称，葡萄球菌辅酶a -二硫还原酶（CoADR）的晶体结构维持了细胞内CoASH的还原状态[Mallett， T.C, Wallen, j.r., Karplus, p.a., Sakai， H., Tsukihara， T., and Claiborne， A.（2006）生物化学45,11278-89]。在本报告中，我们证明了CoASH是炭疽芽孢杆菌的主要硫醇；一项生物信息学分析表明，在大肠杆菌中负责将泛酸盐（Pan）转化为CoASH的四种蛋白质中，有三种在炭疽杆菌中保守。相比之下，一种新的III型泛酸激酶（PanK）催化了炭疽杆菌生物合成途径的第一步；与大肠杆菌I型PanK不同，这种酶不受CoASH的反馈抑制。利用多波长异常色散数据并在2.0 a分辨率下对炭疽芽孢杆菌PanK （BaPanK）的晶体结构进行了解析，表明BaPanK是醋酸糖激酶/Hsc70/肌动蛋白（ASKHA）超家族的新成员。Pan和ATP底物被模拟成活性位点的间隙；除了为缺乏CoASH抑制提供明确的理论基础外，对PAN结合口袋的分析还导致了两个新的基于结构的基序（PAN和INTERFACE基序）的发展。我们的分析还表明，形成孢子的炭疽杆菌中的III型PanK在这种A类生物防御病原体的新型硫醇/二硫氧化还原生物学中起着至关重要的作用。
Coenzyme A (CoASH) is the major low-molecular weight thiol in Staphylococcus aureus and a number of other bacteria; the crystal structure of the S. aureus coenzyme A-disulfide reductase (CoADR), which maintains the reduced intracellular state of CoASH, has recently been reported [Mallett, T.C., Wallen, J.R., Karplus, P.A., Sakai, H., Tsukihara, T., and Claiborne, A. (2006) Biochemistry 45, 11278-89]. In this report we demonstrate that CoASH is the major thiol in Bacillus anthracis; a bioinformatics analysis indicates that three of the four proteins responsible for the conversion of pantothenate (Pan) to CoASH in Escherichia coli are conserved in B. anthracis. In contrast, a novel type III pantothenate kinase (PanK) catalyzes the first committed step in the biosynthetic pathway in B. anthracis; unlike the E. coli type I PanK, this enzyme is not subject to feedback inhibition by CoASH. The crystal structure of B. anthracis PanK (BaPanK), solved using multiwavelength anomalous dispersion data and refined at a resolution of 2.0 A, demonstrates that BaPanK is a new member of the Acetate and Sugar Kinase/Hsc70/Actin (ASKHA) superfamily. The Pan and ATP substrates have been modeled into the active-site cleft; in addition to providing a clear rationale for the absence of CoASH inhibition, analysis of the Pan-binding pocket has led to the development of two new structure-based motifs (the PAN and INTERFACE motifs). Our analyses also suggest that the type III PanK in the spore-forming B. anthracis plays an essential role in the novel thiol/disulfide redox biology of this category A biodefense pathogen.