Type 3 fimbriae, encoded by the conjugative plasmid pOLA52, enhance biofilm formation and transfer frequencies in Enterobacteriaceae strains
Type 3 fimbriae, encoded by the conjugative plasmid pOLA52, enhance biofilm formation and transfer frequencies in Enterobacteriaceae strains
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DOI：
10.1099/mic.0.2007/010454-0
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发表时间：
2008-01-01
期刊：
影响因子：
2.8
通讯作者：
Hansen, Lars Hestbjerg
中科院分区：
文献类型：
--
作者：
Burmolle, Mette;Bahl, Martin Lain;Hansen, Lars Hestbjerg
研究了接合质粒pOLA52促进大肠杆菌生物膜形成的能力，pOLA52通过多药外排泵赋予对喹乙醇和其他抗菌药物的抗性。转座子诱变的pOLA52克隆文库的筛选揭示了几种生物膜缺陷突变体，它们都定位在与肺炎克雷伯氏菌的mrkABCDF操纵子具有高度同源性的推定操纵子内，其中这些基因负责3型菌毛表达、附着于表面和生物膜形成。与具有完整的mrk操纵子的突变体相比，含有具有破坏的推定mrk操纵子的pOLA52的克隆在微量滴定板和导尿管中的生物膜形成分别减少了超过100倍和2倍。当mrk操纵子被破坏时，pOLA52的接合转移率也显著降低。通过逆转录酶分析，证明了推定的mrk操纵子中包含的基因是连锁的，并且可能作为单个操纵子表达。用3型菌毛（MrkA）特异性抗体的免疫印迹进一步证实了3型菌毛的表达。当转移到其他可能致病的肠杆菌科成员，包括肺炎克雷伯氏菌、鼠伤寒沙门氏菌、克鲁维氏菌和产气肠杆菌时，pOLA52促进了生物膜形成的增加。pOLA52被认为是编码3型菌毛的接合质粒的第一个例子，导致携带质粒的菌株的接合频率和生物膜形成的增加。
The conjugative plasmid pOLA52, which confers resistance to olaquindox and other antimicrobial agents through a multidrug efflux pump, was investigated for its ability to promote biofilm formation in Escherichia coli. Screening of a transposon-mutagenized pOLA52 clone library revealed several biofilm-deficient mutants, which all mapped within a putative operon with high homology to the mrkABCDF operon of Klebsiella pneumoniae, where these genes are responsible for type 3 fimbriae expression, attachment to surfaces and biofilm formation. Biofilm formation in microtitre plates and in urinary catheters of clones containing pOLA52 with a disrupted putative mrk operon was reduced by more than 100-fold and 2-fold, respectively, compared to mutants with an intact mrk operon. The conjugative transfer rate of pOLA52 was also significantly lower when the mrk operon was disrupted. Through reverse transcriptase analysis, it was demonstrated that the genes contained in the putative mrk operon were linked and likely to be expressed as a single operon. Immunoblotting with type 3 fimbriae (MrkA)-specific antibodies further verified expression of type 3 fimbriae. When transferred to other, potentially pathogenic, members of the family Enterobacteriaceae, including Klebsiella pneumoniae, Salmonella Typhimurium, Kluyvera sp. and Enterobacter aerogenes, pOLA52 facilitated increased biofilm formation. pOLA52 is believed to represent the first example of a conjugative plasmid encoding type 3 fimbriae, resulting in enhanced conjugation frequencies and biofilm formation of the plasm id-harbouring strain.