Moraxella catarrhalis uses a twin-arginine translocation system to secrete the β-lactamase BRO-2

BMC Microbiology

Research Article

Eric R Lafontaine¹  Rachel Balder¹  Teresa L Shaffer² 

[1] Department of Infectious Diseases, University of Georgia, 30602, Athens, GA, USA;Department of Microbiology, University of Georgia, 30602, Athens, GA, USA;

关键词: Moraxella Catarrhalis;    Nitrocefin;    Twin Arginine Translocation;    Strain O35E;    Signal Sequence Cleavage Site;   

DOI  :  10.1186/1471-2180-13-140

 received in 2013-04-04, accepted in 2013-06-10,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundMoraxella catarrhalis is a human-specific gram-negative bacterium readily isolated from the respiratory tract of healthy individuals. The organism also causes significant health problems, including 15-20% of otitis media cases in children and ~10% of respiratory infections in adults with chronic obstructive pulmonary disease. The lack of an efficacious vaccine, the rapid emergence of antibiotic resistance in clinical isolates, and high carriage rates reported in children are cause for concern. Virtually all Moraxella catarrhalis isolates are resistant to β-lactam antibiotics, which are generally the first antibiotics prescribed to treat otitis media in children. The enzymes responsible for this resistance, BRO-1 and BRO-2, are lipoproteins and the mechanism by which they are secreted to the periplasm of M. catarrhalis cells has not been described.ResultsComparative genomic analyses identified M. catarrhalis gene products resembling the TatA, TatB, and TatC proteins of the well-characterized Twin Arginine Translocation (TAT) secretory apparatus. Mutations in the M. catarrhalis tatA, tatB and tatC genes revealed that the proteins are necessary for optimal growth and resistance to β-lactams. Site-directed mutagenesis was used to replace highly-conserved twin arginine residues in the predicted signal sequence of M. catarrhalis strain O35E BRO-2, which abolished resistance to the β-lactam antibiotic carbanecillin.ConclusionsMoraxella catarrhalis possesses a TAT secretory apparatus, which plays a key role in growth of the organism and is necessary for secretion of BRO-2 into the periplasm where the enzyme can protect the peptidoglycan cell wall from the antimicrobial activity of β-lactam antibiotics.

【 授权许可】

Unknown   
© Balder et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.