Identification of a Potential Membrane-Targeting Sequence in the C-Terminus of the F Plasmid Segregation Protein SopA,The Journal of Membrane Biology

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Identification of a Potential Membrane-Targeting Sequence in the C-Terminus of the F Plasmid Segregation Protein SopA
The Journal of Membrane Biology ( IF 2.3 ) Pub Date : 2021-01-11 , DOI: 10.1007/s00232-020-00157-8
Dipika Mishra ₁ , Sakshi Pahujani _{1,

2} , Nivedita Mitra ₁ , Anand Srivastava ₂ , Ramanujam Srinivasan ₁

Affiliation

Abstract

Stable maintenance and partitioning of the ‘Fertility’ plasmid or the F plasmid in its host Escherichia coli require the function of a ParA superfamily of proteins known as SopA. The mechanism by which SopA mediates plasmid segregation is well studied. SopA is a nucleoid-binding protein and binds DNA in an ATP-dependent but sequence non-specific manner. ATP hydrolysis stimulated by the binding of the SopBC complex mediates the release of SopA from the nucleoid. Cycles of ATP-binding and hydrolysis generate an ATPase gradient that moves the plasmid through a chemophoresis force. Nucleoid binding of SopA thus assumes a central role in its plasmid-partitioning function. However, earlier work also suggests that the F plasmid can be partitioned into anucleate cells, thus implicating nucleoid independent partitioning. Interestingly, SopA is also reported to be associated with the inner membrane of the bacteria. Here, we report the identification of a possible membrane-targeting sequence, a predicted amphipathic helix, at the C-terminus of SopA. Molecular dynamics simulations indicate that the predicted amphipathic helical motif of SopA has weak affinity for membranes. Moreover, we experimentally show that SopA can associate with bacterial membranes, is detectable in the membrane fractions of bacterial lysates, and is sensitive to the membrane potential. Further, unlike the wild-type SopA, a deletion of the C-terminal 29 amino acids results in the loss of F plasmids from bacterial cells.

Graphic Abstract

中文翻译：

F质粒分离蛋白SopA C端潜在膜靶向序列的鉴定

摘要

'Fertility' 质粒或 F 质粒在其宿主大肠杆菌中的稳定维持和分配需要称为 SopA 的 ParA 蛋白质超家族的功能。SopA 介导质粒分离的机制已得到充分研究。SopA 是一种类核结合蛋白，以 ATP 依赖性但序列非特异性方式结合 DNA。由 SopBC 复合物的结合刺激的 ATP 水解介导了 SopA 从类核中的释放。ATP 结合和水解循环产生 ATP 酶梯度，使质粒通过化学电泳力移动。因此，SopA 的核苷结合在其质粒分配功能中发挥着核心作用。然而，早期的工作也表明 F 质粒可以被分配到无核细胞中，因此暗示了与核素无关的分配。有趣的是，据报道 SopA 也与细菌的内膜有关。这里，我们报告了在 SopA 的 C 末端发现了一个可能的膜靶向序列，即预测的两亲性螺旋。分子动力学模拟表明，预测的 SopA 两亲螺旋基序对膜的亲和力较弱。此外，我们通过实验表明 SopA 可以与细菌膜结合，在细菌裂解物的膜组分中可检测到，并且对膜电位敏感。此外，与野生型 SopA 不同，C 末端 29 个氨基酸的缺失导致 F 质粒从细菌细胞中丢失。我们通过实验证明 SopA 可以与细菌膜结合，在细菌裂解物的膜组分中可检测到，并且对膜电位敏感。此外，与野生型 SopA 不同，C 末端 29 个氨基酸的缺失导致 F 质粒从细菌细胞中丢失。我们通过实验证明 SopA 可以与细菌膜结合，在细菌裂解物的膜组分中可检测到，并且对膜电位敏感。此外，与野生型 SopA 不同，C 末端 29 个氨基酸的缺失导致 F 质粒从细菌细胞中丢失。

图形摘要

更新日期：2021-01-11

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