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首页> 外文期刊>Journal of bacteriology >OmpA Is the Principal Nonspecific Slow Porin of Acinetobacter baumannii
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OmpA Is the Principal Nonspecific Slow Porin of Acinetobacter baumannii

机译：OmpA是鲍曼不动杆菌的主要非特异性慢孔蛋白

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Acinetobacter species show high levels of intrinsic resistance to many antibiotics. The major protein species in the outer membrane of Acinetobacter baumannii does not belong to the high-permeability trimeric porin family, which includes Escherichia coli OmpF/OmpC, and instead is a close homolog of E. coli OmpA and Pseudomonas aeruginosa OprF. We characterized the pore-forming function of this OmpA homolog, OmpAAb, by a reconstitution assay. OmpAAb produced very low pore-forming activity, about 70-fold lower than that of OmpF and an activity similar to that of E. coli OmpA and P. aeruginosa OprF. The pore size of the OmpAAb channel was similar to that of OprF, i.e., about 2 nm in diameter. The low permeability of OmpAAb is not due to the inactivation of this protein during purification, because the permeability of the whole A. baumannii outer membrane was also very low. Furthermore, the outer membrane permeability to cephalothin and cephaloridine, measured in intact cells, was about 100-fold lower than that of E. coli K-12. The permeability of cephalothin and cephaloridine in A. baumannii was decreased 2- to 3-fold when the ompAAb gene was deleted. These results show that OmpAAb is the major nonspecific channel in A. baumannii. The low permeability of this porin, together with the presence of constitutive β-lactamases and multidrug efflux pumps, such as AdeABC and AdeIJK, appears to be essential for the high levels of intrinsic resistance to a number of antibiotics.
机译：不动杆菌对许多抗生素表现出很高的内在抗性。鲍曼不动杆菌外膜中的主要蛋白质种类不属于高渗透性三聚体孔蛋白家族，其包括大肠杆菌OmpF / OmpC，而是与大肠杆菌OmpA和铜绿假单胞菌OprF的紧密同源。我们通过重构分析表征了该OmpA同源物OmpA Ab 的成孔功能。 OmpA Ab 产生的成孔活性非常低，比OmpF低约70倍，并且活性类似于大肠杆菌OmpA和铜绿假单胞菌OprF。 OmpA Ab 通道的孔径与OprF相似，即直径约为2 nm。 OmpA Ab 的低渗透性并不是由于该蛋白在纯化过程中失活，因为整个鲍曼不动杆菌外膜的渗透性也非常低。此外，在完整细胞中测得的对头孢菌素和头孢啶的外膜通透性比大肠杆菌K-12低约100倍。删除 ompA Ab 基因后，鲍曼不动杆菌的头孢菌素和头孢啶含量降低了2-3倍。这些结果表明，OmpA Ab 是鲍曼不动杆菌的主要非特异性通道。这种孔蛋白的低渗透性，以及构成性β-内酰胺酶和多药外排泵（如AdeABC和AdeIJK）的存在，对于高水平对多种抗生素的内在耐药性至关重要。

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