The gain-of-function allele bamAE470K bypasses the essential requirement for BamD in β-barrel outer membrane protein assembly
The gain-of-function allele bamAE470K bypasses the essential requirement for BamD in β-barrel outer membrane protein assembly
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DOI：
10.1073/pnas.2007696117
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发表时间：
2020-08-04
影响因子：
11.1
通讯作者：
Silhavy, Thomas J.
中科院分区：
文献类型：
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作者：
Hart, Elizabeth M.;Gupta, Meera;Silhavy, Thomas J.
革兰氏阴性菌的外膜（OM）赋予对毒素和抗生素的先天抗性。整合β-桶外膜蛋白（OMP）的功能是建立和维持OM的选择性渗透性。OMPs通过β-桶组装机（BAM）组装成OM，BAM由一种OMP-BamA-和四种脂蛋白-BamB、C、D和E组成。BamB、C和E可以单独去除，对屏障功能只有很小的影响;然而，BamA或BamD的缺失会导致OMP组装的整体缺陷，并导致细胞死亡。我们已经确定了一个功能获得性突变bamA（E470 K），它绕过了对BamD的要求。虽然bamD：：kan bamA（E470 K）细胞表现出生长和OM屏障缺陷，但它们组装OMP具有令人惊讶的稳健性。我们的研究结果表明，BamD不发挥催化作用，在OMP组装，而是功能调节BamA的活性。
The outer membrane (OM) of gram-negative bacteria confers innate resistance to toxins and antibiotics. Integral beta-barrel outer membrane proteins (OMPs) function to establish and maintain the selective permeability of the OM. OMPs are assembled into the OM by the beta-barrel assembly machine (BAM), which is composed of one OMP-BamA-and four lipoproteins-BamB, C, D, and E. BamB, C, and E can be removed individually with only minor effects on barrier function; however, depletion of either BamA or BamD causes a global defect in OMP assembly and results in cell death. We have identified a gain-of-function mutation, bamA(E470K), that bypasses the requirement for BamD. Although bamD::kan bamA(E470K) cells exhibit growth and OM barrier defects, they assemble OMPs with surprising robustness. Our results demonstrate that BamD does not play a catalytic role in OMP assembly, but rather functions to regulate the activity of BamA.