Molecular characterization of oxacillinase 72 (OXA-72) associated proteins from Acinetobacter baumannii

• Main Authors: Wei-Chui Tai, 戴維萩
• Other Authors: Wen-Long Cho
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/93805263094692141452

碩士 === 國立陽明大學 === 臨床醫學研究所 === 99 === Acinetobacter baumannii is a gram-negative coccobacillus. In the past three decades it has emerged from an organism of questionable pathogenicity to an important opportunistic pathogen causing nosocomial infections, particularly in intensive care units. The emergence of strains that are resistant to almost all commercially available antibiotics, even though carbapenems have been the choice for serious A. baumannii infections. An efficient mechanism to resist carbapenem in A. baumannii mostly related to Class D β-lactamases (Carbapenem hydrolyzing oxacillinases, CHDLs) production. An OXA-72 gene was isolated from a plasmid carried by a multi-drug resistant isolate SK44. The open reading frame is about 825 base pairs encoding an oxacillinase. There are two copies of OXA-72 located at the same plasmid with different upstream regions, and the both genes with their corresponding upstream regions (about 1.5 kb for copy1 and 1.8 kb for copy2) were cloned into shuttle plasmids for transformation into Acinetobacter baumannii (Ab290) and E.coli (DH5α). Our results revealed that OXA-72 in Ab290 had higher anti-antibiotic activity than that in DH5α. In addition, OXA-72 protein was found to be liberated from Ab290-OXA-72 cells and it provided imipenem resistance for E.coli. In previous experiments discovered an obvious protein band associated with OXA-72 during OXA-72 fusion protein purification. This band was separated from SDS-PAGE for LC-MS/MS identification. Four putative OXA-72 associated peptides (OXA-72 BP-A, -B, -C, and -D) were resolved, and their corresponding DNA sequence were cloned and sequenced. The preliminary results of co-immunoprecipitaion revealed that OXA-72 had good binding ability with OXA-72 BP-B. The real functions of OXA-72 BP-B protein will be investigated in the future.