期刊
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY
卷 60, 期 3, 页码 1509-1514出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/AAC.02444-15
关键词
-
资金
- HHS \ NIH \ National Institute of Allergy and Infectious Diseases (NIAID) [AI065357]
Burkholderia pseudomallei is the etiologic agent of melioidosis, a difficult-to-treat disease with diverse clinical manifestations. beta-Lactam antibiotics such as ceftazidime are crucial to the success of melioidosis therapy. Ceftazidime-resistant clinical isolates have been described, and the most common mechanism is point mutations affecting expression or critical amino acid residues of the chromosomally encoded class A PenA beta-lactamase. We previously showed that PenA was exported via the twin arginine translocase system and associated with the spheroplast fraction. We now show that PenA is a membrane-bound lipoprotein. The protein and accompanying beta-lactamase activity are found in the membrane fraction and can be extracted with Triton X-114. Treatment with globomycin of B. pseudomallei cells expressing PenA results in accumulation of the prolipoprotein. Mass spectrometric analysis of extracted membrane proteins reveals a protein peak whose mass is consistent with a triacylated PenA protein. Mutation of a crucial lipobox cysteine at position 23 to a serine residue results in loss of beta-lactamase activity and absence of detectable PenA(C23S) protein. A concomitant isoleucine-to-alanine change at position 20 in the signal peptide processing site in the PenA(C23S) mutant results in a nonlipidated protein (PenA(I20A C23S)) that is processed by signal peptidase I and exhibits beta-lactamase activity. The resistance profile of a B. pseudomallei strain expressing this protein is indistinguishable from the profile of the isogenic strain expressing wild-type PenA. The data show that PenA membrane association is not required for resistance and must serve another purpose.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据