Structure of the Bacillus anthracis Sortase A Enzyme Bound to Its Sorting Signal A FLEXIBLE AMINO-TERMINAL APPENDAGE MODULATES SUBSTRATE ACCESS
Structure of the Bacillus anthracis Sortase A Enzyme Bound to Its Sorting Signal A FLEXIBLE AMINO-TERMINAL APPENDAGE MODULATES SUBSTRATE ACCESS
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DOI：
10.1074/jbc.m115.670984
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发表时间：
2015-10-16
影响因子：
4.8
通讯作者：
Clubb, Robert T.
中科院分区：
文献类型：
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作者：
Chan, Albert H.;Yi, Sung Wook;Clubb, Robert T.
内生孢子形成细菌炭疽芽孢杆菌在人类和动物中引起致命的炭疽病。这种病原体在巨噬细胞内复制的能力取决于通过B附着于细胞壁的细菌表面蛋白的展示。炭疽菌分选酶A（（Ba）SrtA）酶。以前，我们发现A类（Ba）SrtA分选酶含有一个独特的N-末端附件，它包裹在蛋白质的主体周围，与酶的活性位点接触。为了深入了解其功能，我们确定了与LPXTG分选信号类似物结合的（Ba）SrtA的NMR结构。结构，结合动力学，动力学，和全细胞蛋白质显示数据表明，N末端调节底物进入酶。我们建议，它可以通过减少细胞壁锚定反应过程中形成的酶-蛋白质共价中间体的非生产性水解裂解来提高蛋白质展示的效率。值得注意的是，关键活性位点环（β 7/β 8环）在结合分选信号后经历无序到有序的转变，潜在地促进脂质II的识别。
The endospore forming bacterium Bacillus anthracis causes lethal anthrax disease in humans and animals. The ability of this pathogen to replicate within macrophages is dependent upon the display of bacterial surface proteins attached to the cell wall by the B. anthracis Sortase A ((Ba)SrtA) enzyme. Previously, we discovered that the class A (Ba)SrtA sortase contains a unique N-terminal appendage that wraps around the body of the protein to contact the active site of the enzyme. To gain insight into its function, we determined the NMR structure of (Ba)SrtA bound to a LPXTG sorting signal analog. The structure, combined with dynamics, kinetics, and whole cell protein display data suggest that the N terminus modulates substrate access to the enzyme. We propose that it may increase the efficiency of protein display by reducing the unproductive hydrolytic cleavage of enzyme-protein covalent intermediates that form during the cell wall anchoring reaction. Notably, a key active site loop (beta 7/beta 8 loop) undergoes a disordered to ordered transition upon binding the sorting signal, potentially facilitating recognition of lipid II.