Acinetobacter baumannii 為一種伺機性的致病菌，經常可見於免疫缺陷的病人身上。Acinetobacter baumannii 的感染通常不易治療，其和具有多重抗藥性的能力有關。有研究報導指出，Acineto -bacter baumannii擁有不只一種以上的抗藥性系統。然而，其抗藥機制卻仍尚未被證實。在本篇論文中，將探討類似MFS (multidrug facilitator superfamily) 抗藥性功能的基因。首先，使用PCR的方法由Acinetobacter baumannii 的chromosomal DNA上選殖出類似MFS的基因，取名為Amr。此Amr基因經由定序結果得知具有1,536個核酸，且可產生一個擁有511個胺基酸的ORF (open reading frame)。此外，其胺基酸序列和大腸桿菌上所具有的多重抗藥性EmrB基因擁有高度的相似性。雖然在SDS-PAGE上無法觀測到Amr的蛋白表現，但轉殖至大腸桿菌上的Amr基因卻對carbonlcyanide m-chlorophenylhydrazone (CCCP) 和nalidixic acid 具有抵抗的能力。此外，Amr基因對CCCP所產生的抗性機轉為一種pH-independent的形式，但對nalidixic acid而言則為pH-dependent。因此，我們猜測proton motive force (pmf) 並不是促使Amr 產生抗藥性的唯一方式。 Acinetobacter baumannii is an opportunistic pathogen found in hospital infections to immunocompromised patients. A. baumannii infections sometime are very difficult to treat due to its frequently associated with multidrug resistance. Previous study has shown that more than one efflux systems mediate antibiotic resistance in A. baumannii. However, A. baumannii resistant determinant has not been fully defined yet. In this thesis study, we characterized the MFS-like multidrug resistant gene and its function for the resistance phenomena. Using PCR, we have cloned and expressed A. baumannii MFS-like gene, named Amr (Acinetobacter multidrug resistance). The Amr contains 1,536 bp in length and encodes an open reading frame (ORF) deduced a protein of 511 amino acid residues in number. The deduced amino acid sequence is homologous to emrB, a multidrug-resistance pump from E. coli. Even though the predicted Amr protein is not visualized by SDS-PAGE analysis, however, when transformed the Amr gene into E. coli, the cell acquired the gene becomes resistances to carbonlcyanide m-chlorophenylhydrazone (CCCP) and nalidixic acid. Moreover, Amr mediates resistance to CCCP is in a pH-independent manner, while resistance to nalidixic acid is in a pH-dependent manner. We suggest that the proton motive force (pmf) might not be the absolute factor for Amr resistance activity.
