首页> 外文OA文献 >The Penicillin sensory transducer, blar, involved in the inducibility of beta-lactamase synthesis in bacillus licheniformis is embedded in the plasma membrane via a four-alpha-helix bundle
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The Penicillin sensory transducer, blar, involved in the inducibility of beta-lactamase synthesis in bacillus licheniformis is embedded in the plasma membrane via a four-alpha-helix bundle

机译:涉及地衣芽孢杆菌中β-内酰胺酶合成的可诱导性的青霉素感觉传感器blar通过四α-螺旋束嵌入质膜中

摘要

Prediction studies, conformational analyses and membrane-topology mapping lead to the conclusion that the penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in Bacillus licheniformis, is embedded in the plasma membrane bilayer via four transmembrane segments TM1-TM4 that forma four-alpha-helix bundle. The extracellular 262-amino-acid-residue polypeptide, S340-R601, that is fused at the carboxy end of TM4, possesses the amino acid sequence signature of a penicilloyl serine transferase. It probably functions as penicillin sensor. As an independent entity, this polypeptide behaves as a high-affinity penicillin-binding protein. As a component of the full-size BlaR, it adopts a different conformation presumably because of interactions with the extracellular 63-amino-acid-residue P53-S115 loop that connects TM2 and TM3.Reception of the penicillin-induced signal requires a precise conformation of the sensor but it does not involve penicilloylation of the serine residue S402 of motif STYK. Signal transmission through the plasma membrane by the four-alpha-helix bundle may proceed in a way comparable to that of the aspartate receptor, Tar. Signal emission in the cytosol by the intracellular 189-amino-acid-residue Y134-K322 loop that connects TM3 and TM4, may proceed via the activation of a putative metallopeptidase.
机译:预测研究,构象分析和膜拓扑图得出的结论是,涉及地衣芽孢杆菌β-内酰胺酶合成诱导性的青霉素感觉传感器BlaR通过四个跨膜区段TM1-TM4嵌入质膜双层中,从而形式四-α-螺旋束。在TM4的羧基端融合的细胞外262个氨基酸残基的多肽,S340-R601,具有青霉酰丝氨酸转移酶的氨基酸序列特征。它可能充当青霉素传感器。作为一个独立的实体,该多肽具有高亲和力的青霉素结合蛋白的功能。作为全尺寸BlaR的组成部分,它可能采用不同的构象,可能是因为与连接TM2和TM3的细胞外63个氨基酸残基P53-S115环相互作用所致。接收青霉素诱导的信号需要精确的构象。但是,它不涉及基序STYK的丝氨酸残基S402的青霉酰化。四-α-螺旋束穿过质膜的信号传输可能以与天冬氨酸受体Tar相当的方式进行。连接TM3和TM4的细胞内189个氨基酸残基Y134-K322环在胞质中发射信号的过程可能是通过假定的金属肽酶的激活进行的。

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