Acyl-chain selectivity and physiological roles of Staphylococcus aureus fatty acid-binding proteins
Acyl-chain selectivity and physiological roles of Staphylococcus aureus fatty acid-binding proteins
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DOI：
10.1074/jbc.ra118.006160
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发表时间：
2019-01-04
影响因子：
4.8
通讯作者：
Rock, Charles O.
中科院分区：
文献类型：
--
作者：
Cuypers, Maxime G.;Subramanian, Chitra;Rock, Charles O.
脂肪酸（FA）激酶产生酰基磷酸盐，用于革兰氏阳性细菌病原体中膜磷脂的合成。FA激酶由激酶蛋白（FakA）组成，其磷酸化与第二模块（FA结合蛋白（FakB））结合的FA底物。金黄色葡萄球菌表达两种不同但相关的FakB，具有不同的FA选择性。在这里，我们报告的结构FakB 1结合到四个饱和的FA在1.6-1.93分辨率。我们观察到，不同的FA结构被容纳在一个稍微弯曲的疏水腔，其长度是由隧道末端的异亮氨酸侧链的构象。FakB 1中的疏水通道阻止了顺式不饱和脂肪酸的结合，而FakB 2蛋白中的扭结通道则容纳了顺式不饱和脂肪酸。FakB内部的差异不会传播到蛋白质的表面，从而保留了与它们的三个共同伙伴FakA，PlsX和PlsY的蛋白质-蛋白质相互作用。使用细胞热位移分析，我们发现，FakB 1结合FA在体内，而一个显着比例的FakB 2不。外源性FA掺入fakB 1和fakB 2 S中的磷脂中。金黄色葡萄球菌敲除菌株揭示了FakB 1不能有效地激活不饱和FA。FakB 2喜欢不饱和FA，但也允许掺入饱和FA。这些结果与FakB 1主要在S.金黄色葡萄球菌代谢，而FakB 2激活宿主衍生的油酸，而S.金黄色葡萄球菌不产生，但在感染部位大量存在。
Fatty acid (FA) kinase produces acyl-phosphate for the synthesis of membrane phospholipids in Gram-positive bacterial pathogens. FA kinase consists of a kinase protein (FakA) that phosphorylates an FA substrate bound to a second module, an FA-binding protein (FakB). Staphylococcus aureus expresses two distinct, but related, FakBs with different FA selectivities. Here, we report the structures of FakB1 bound to four saturated FAs at 1.6-1.93 resolution. We observed that the different FA structures are accommodated within a slightly curved hydrophobic cavity whose length is governed by the conformation of an isoleucine side chain at the end of the tunnel. The hydrophobic tunnel in FakB1 prevents the binding of cis-unsaturated FAs, which are instead accommodated by the kinked tunnel within the FakB2 protein. The differences in the FakB interiors are not propagated to the proteins' surfaces, preserving the protein-protein interactions with their three common partners, FakA, PlsX, and PlsY. Using cellular thermal shift analyses, we found that FakB1 binds FA in vivo, whereas a significant proportion of FakB2 does not. Incorporation of exogenous FA into phospholipid in fakB1 and fakB2 S. aureus knockout strains revealed that FakB1 does not efficiently activate unsaturated FAs. FakB2 preferred unsaturated FAs, but also allowed the incorporation of saturated FAs. These results are consistent with a model in which FakB1 primarily functions in the recycling of the saturated FAs produced by S. aureus metabolism, whereas FakB2 activates host-derived oleate, which S. aureus does not produce but is abundant at infection sites.