SmeT 的结构和功能分析，嗜麦芽窄食单胞菌多药外排泵 SmeDEF 的阻遏物。,Journal of Biological Chemistry

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SmeT 的结构和功能分析，嗜麦芽窄食单胞菌多药外排泵 SmeDEF 的阻遏物。
Journal of Biological Chemistry ( IF 4.0 ) Pub Date : 2009 May 22 , DOI: 10.1074/jbc.m809221200
Alvaro Hernández ₁ , María J Maté , Patricia C Sánchez-Díaz , Antonio Romero , Fernando Rojo , José L Martínez

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嗜麦芽窄食单胞菌是一种条件致病菌，其特征是对几种抗生素的内在低敏感性。这种低敏感性部分依赖于染色体编码的多药外排泵的表达，SmeDEF 是迄今为止在该细菌物种中研究的最相关的抗生素抗性外排泵。smeDEF 的表达在其互补 DNA 链中被上游 smeDEF 编码的 SmeT 阻遏物下调。在本文中，我们介绍了 SmeT 的晶体结构并分析了它与其同源算子的相互作用。与转录抑制因子 TetR 家族的其他成员一样，SmeT 表现为二聚体，并呈现出与其他 TetR 蛋白（如 TtgR、QacR 和 TetR）的一些共同结构特征。与结构可用的其他 TetR 蛋白不同，事实证明，SmeT 在 N 和 C 末端有两个可能与其功能相关的扩展。此外，SmeT 提供了迄今为止在 TetR 转录阻遏物家族中描述的最小结合口袋，这可能与特定类型和范围的效应物相关。体外研究表明，SmeT 与一个 28 bp 的假回文区域结合，形成两个复合物。发现该操纵子区域与 smeT 和 smeDEF 的启动子重叠。这一发现与 SmeT 同时下调 smeT 和 smeDEF 转录的作用一致，这可能是由于 RNA 聚合酶与 DNA 结合的空间位阻。这可能与特定类型和范围的效应器相关。体外研究表明，SmeT 与一个 28 bp 的假回文区域结合，形成两个复合物。发现该操纵子区域与 smeT 和 smeDEF 的启动子重叠。这一发现与 SmeT 同时下调 smeT 和 smeDEF 转录的作用一致，这可能是由于 RNA 聚合酶与 DNA 结合的空间位阻。这可能与特定类型和范围的效应器相关。体外研究表明，SmeT 与一个 28 bp 的假回文区域结合，形成两个复合物。发现该操纵子区域与 smeT 和 smeDEF 的启动子重叠。这一发现与 SmeT 同时下调 smeT 和 smeDEF 转录的作用一致，这可能是由于 RNA 聚合酶与 DNA 结合的空间位阻。

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Structural and functional analysis of SmeT, the repressor of the Stenotrophomonas maltophilia multidrug efflux pump SmeDEF.

Stenotrophomonas maltophilia is an opportunistic pathogen characterized for its intrinsic low susceptibility to several antibiotics. Part of this low susceptibility relies on the expression of chromosomally encoded multidrug efflux pumps, with SmeDEF being the most relevant antibiotic resistance efflux pump so far studied in this bacterial species. Expression of smeDEF is down-regulated by the SmeT repressor, encoded upstream smeDEF, in its complementary DNA strand. In the present article we present the crystal structure of SmeT and analyze its interactions with its cognate operator. Like other members of the TetR family of transcriptional repressors, SmeT behaves as a dimer and presents some common structural features with other TetR proteins like TtgR, QacR, and TetR. Differing from other TetR proteins for which the structure is available, SmeT turned out to have two extensions at the N and C termini that might be relevant for its function. Besides, SmeT presents the smallest binding pocket so far described in the TetR family of transcriptional repressors, which may correlate with a specific type and range of effectors. In vitro studies revealed that SmeT binds to a 28-bp pseudopalindromic region, forming two complexes. This operator region was found to overlap the promoters of smeT and smeDEF. This finding is consistent with a role for SmeT simultaneously down-regulating smeT and smeDEF transcription, likely by steric hindrance on RNA polymerase binding to DNA.

更新日期：2017-01-31

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