Channel Formation by CarO, the Carbapenem Resistance-Associated Outer Membrane Protein of Acinetobacter baumannii
Channel Formation by CarO, the Carbapenem Resistance-Associated Outer Membrane Protein of Acinetobacter baumannii
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CarO（鲍曼不动杆菌碳青霉烯类耐药相关外膜蛋白）的通道形成
DOI：
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发表时间：
2005
影响因子：
4.9
通讯作者：
E. Dé
中科院分区：
文献类型：
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作者：
A. Siroy;V. Molle;C. Lemaître;D. Vallenet;M. Pestel;A. Cozzone;T. Jouenne;E. Dé
摘要最近研究表明，多重耐药鲍曼不动杆菌临床菌株对亚胺培南和美罗培南的耐药性与热修饰的25/29-kDa外膜蛋白（称为CarO）的丢失有关。本研究旨在研究CarO的通道形成特性。对该蛋白条带的质谱分析检测到另一种25 kDa蛋白（称为Omp 25）以及CarO。两种蛋白质呈现相似的理化参数（Mw和pI）。我们过量生产并纯化了两种多肽作为His标记的重组蛋白。圆二色谱分析表明，这些蛋白质的二级结构主要为β-链构象，具有典型的孔蛋白的光谱特征。我们研究了蛋白质的通道形成特性，通过重组成人工脂质双层。在这些条件下，CarO诱导离子通道的电导值为110 pS在1 M KCl，而Omp 25蛋白没有形成任何通道，尽管其建议的孔蛋白功能。由CarO形成的孔显示出轻微的阳离子选择性和无电压闭合。在CarO中没有发现特异性亚胺培南结合位点，该蛋白质宁愿形成非特异性单体通道。
ABSTRACT It has been recently shown that resistance to both imipenem and meropenem in multidrug-resistant clinical strains of Acinetobacter baumannii is associated with the loss of a heat-modifiable 25/29-kDa outer membrane protein, called CarO. This study aimed to investigate the channel-forming properties of CarO. Mass spectrometry analyses of this protein band detected another 25-kDa protein (called Omp25), together with CarO. Both proteins presented similar physicochemical parameters (Mw and pI). We overproduced and purified the two polypeptides as His-tagged recombinant proteins. Circular dichroism analyses demonstrated that the secondary structure of these proteins was mainly a β-strand conformation with spectra typical of porins. We studied the channel-forming properties of proteins by reconstitution into artificial lipid bilayers. In these conditions, CarO induced ion channels with a conductance value of 110 pS in 1 M KCl, whereas the Omp25 protein did not form any channels, despite its suggested porin function. The pores formed by CarO showed a slight cationic selectivity and no voltage closure. No specific imipenem binding site was found in CarO, and this protein would rather form unspecific monomeric channels.