The ATP-binding cassette transporter Cbc (choline/betaine/carnitine) recruits multiple substrate-binding proteins with strong specificity for distinct quaternary ammonium compounds.
The ATP-binding cassette transporter Cbc (choline/betaine/carnitine) recruits multiple substrate-binding proteins with strong specificity for distinct quaternary ammonium compounds.
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DOI：
10.1111/j.1365-2958.2009.06962.x
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发表时间：
2010-01
影响因子：
3.6
通讯作者：
Beattie GA
中科院分区：
文献类型：
--
作者：
Chen C;Malek AA;Wargo MJ;Hogan DA;Beattie GA
我们从丁香假单胞菌和铜绿假单胞菌中鉴定出一种胆碱、甜菜碱和肉碱转运蛋白，命名为 Cbc，它在 ATP 结合盒 (ABC) 转运蛋白家族的成员中是不寻常的，因为它使用对其底物具有高度特异性的多种周质底物结合蛋白 (SBP)。由 cbcXWV 操纵子 CbcX 编码的 SBP 以高亲和力 (Km, 2.6 μM) 结合胆碱，尽管它也结合甜菜碱 (Km, 24.2 μM)，但在胆碱存在的情况下不会发生 CbcXWV 介导的甜菜碱摄取。来自苜蓿中华根瘤菌的 CbcX 直系同源物 ChoX 在这些结合特性方面与 CbcX 相似。核心转运蛋白 CbcWV 还与肉碱特异性 SBP CaiX（Km，24 μM）和甜菜碱特异性 SBP BetX（Km，0.6 μM）相互作用。与大多数 ABC 转运蛋白基因座不同，caiX、betX 和 cbcXWV 在基因组中是分开的。只有当 CbcX 和 BetX 与各自的配体结合时，CaiX 介导的肉碱摄取才会减少，这为 ABC 转运蛋白对配体结合的 SBP 的亲和力高于无配体的 SBP 提供了第一个体内证据。这些研究不仅表明 Cbc 转运蛋白可以作为探索 ABC 转运蛋白成分相互作用的有用模型，而且细菌基因组中常见的孤儿 SBP 基因可以编码功能性 SBP。
We identified a choline, betaine and carnitine transporter, designated Cbc, from Pseudomonas syringae and Pseudomonas aeruginosa that is unusual among members of the ATP-binding cassette (ABC) transporter family in its use of multiple periplasmic substrate-binding proteins (SBPs) that are highly specific for their substrates. The SBP encoded by the cbcXWV operon, CbcX, binds choline with a high affinity (Km, 2.6 μM) and, although it also binds betaine (Km, 24.2 μM), CbcXWV-mediated betaine uptake did not occur in the presence of choline. The CbcX orthologue ChoX from Sinorhizobium meliloti was similar to CbcX in these binding properties. The core transporter CbcWV also interacts with the carnitine-specific SBP CaiX (Km, 24 μM) and the betaine-specific SBP BetX (Km, 0.6 μM). Unlike most ABC transporter loci, caiX, betX and cbcXWV are separated in the genome. CaiX-mediated carnitine uptake was reduced by CbcX and BetX only when they were bound by their individual ligands, providing the first in vivo evidence for a higher affinity for ligand-bound than ligand-free SBPs by an ABC transporter. These studies demonstrate not only that the Cbc transporter serves as a useful model for exploring ABC transporter component interactions, but also that the orphan SBP genes common to bacterial genomes can encode functional SBPs.
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影响因子：
14.9
作者：
Jensen LJ;Kuhn M;Stark M;Chaffron S;Creevey C;Muller J;Doerks T;Julien P;Roth A;Simonovic M;Bork P;von Mering C
通讯作者：
von Mering C
影响因子：
3.2
作者：
Buchet, A;Eichler, K;Mandrand-Berthelot, MA
通讯作者：
Mandrand-Berthelot, MA
影响因子：
4.8
作者：
Ames, GFL;Liu, CE;Nikaido, K
通讯作者：
Nikaido, K
DOI：
10.1073/pnas.78.10.6038
发表时间：
1981-01-01
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES
影响因子：
--
作者：
HIGGINS, CF;AMES, GFL
通讯作者：
AMES, GFL
影响因子：
3.6
作者：
Calcagno Galvao, Teca;de Lorenzo, Victor;Canovas, David
通讯作者：
Canovas, David