Beijing Key Laboratory of Bioelectromagnetics, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.
Curr Microbiol. 2012 Jun;64(6):515-23. doi: 10.1007/s00284-012-0099-2. Epub 2012 Mar 1.
Magnetotactic bacteria are a group of prokaryotes capable of sensing and navigating along the earth's magnetic field. The linear alignment of magnetosomes, which acts as a compass needle for orientation, is dependent on the proteins MamJ (amb0964) & MamK (amb0965). We constructed Magnetospirillum magneticum AMB-1 two-hybrid DNA libraries by fusing the random genomic fragments of AMB-1 to the N-terminal domain of the α-subunit of RNA polymerase in vector pTRG and used as preys. The genes mamJ & mamK were cloned in frame with the λ repressor protein (λ cI) in vector pBT and used as baits for screening the binding partners. After preliminary screening, we further confirmed the candidate interactions between selected protein pairs. The results showed that there were relatively strong interactions between MamK versus Amb3498 (flagella motor switch protein fliM), versus Amb0854 MCPs (signal domain of methyl-accepting chemotaxis protein) and versus Amb3568 (GGDEF domain-containing protein), respectively. MamJ versus Amb1722 (hypothetical protein), MamJ versus MamK, and MamK versus Amb1807 (cation transport ATPase) exhibited low level of interaction. Although the TPR repeat protein MamA (amb0971) showed no interaction with either MamJ or MamK, the TPR repeat protein Amb0024 with more motif sequences exhibited relatively strong interaction with MamK. Among the identified proteins, all categorized as signal transduction-related displayed interaction only with MamK and without MamJ, suggesting that magnetotaxis via MamK in Magnetospirillum magneticum AMB-1 might be somehow concerned with the widely accepted chemotaxis mechanism in bacteria.
趋磁细菌是一类能够感知和沿着地球磁场导航的原核生物。磁小体的线性排列作为定向的罗盘针，依赖于蛋白 MamJ（amb0964）和 MamK（amb0965）。我们通过将 AMB-1 的随机基因组片段融合到载体 pTRG 的 RNA 聚合酶α亚基的 N 端结构域中，构建了趋磁螺菌 AMB-1 双杂交 DNA 文库，并将其用作诱饵。mamJ 和 mamK 基因与 λ 阻遏蛋白（λ cI）在载体 pBT 中框内克隆，并用作筛选结合伴侣的诱饵。经过初步筛选，我们进一步证实了所选蛋白对之间的候选相互作用。结果表明，MamK 与 Amb3498（鞭毛运动开关蛋白 fliM）、与 Amb0854 MCPs（甲基接受趋化性蛋白的信号域）和与 Amb3568（含有 GGDEF 结构域的蛋白）之间存在相对较强的相互作用。MamJ 与 Amb1722（假设蛋白）、MamJ 与 MamK 以及 MamK 与 Amb1807（阳离子转运 ATP 酶）之间表现出低水平的相互作用。尽管 TPR 重复蛋白 MamA（amb0971）与 MamJ 或 MamK 均无相互作用，但具有更多 motif 序列的 TPR 重复蛋白 Amb0024 与 MamK 表现出较强的相互作用。在鉴定出的蛋白质中，所有归类为信号转导相关的蛋白质仅与 MamK 相互作用，而与 MamJ 无相互作用，这表明趋磁螺菌 AMB-1 中的磁导向途径与细菌中广泛接受的趋化机制有关。
