ntified the presence of one component system homologue in K. pneumoniae. Thus it is not only important to decode the regulatory cascade of the TCS but it is also imperative to understand the correlation between the one component system and TCS to get an overview of global signaling networks in clinically significant pathogens. Thus, characterizing the functions of CpxAR operon marks just the beginning by in itself. In summary, this study provides preliminary experimental evidence for the participation of cell envelope stress 20008854 response system CpxAR in mediating resistance against GI stresses, antibiotics and disinfectants in K. pneumoniae NTUH-K2044; hyper virulent K1 serotype for the very first time. Materials and Methods Bacterial strains, plasmids and media K. pneumoniae NTUH-K2044 was kindly provided by Dr. Jin Town Wang of the Danoprevir web National Taiwan University Hospital, Taipei, Taiwan. E. coli S17-1l pir which carries the F plasmid and encodes p protein essential for replication of pUT-Km was used for cloning experiments. pUT-Km was used to create insertion-duplication mutations by homologous recombination. Bacteria cultures were grown in Luria-Bertani broth or on LB agar at 37uC with constant shaking and supplemented with Kanamycin where required. The strains were harvested and stored at 280uC before use. CpxAR Confers b-Lactam Resistance DNA methods Restriction digestion, ligation, transformation, and agarose gel electrophoresis were done according to standard protocols. Plasmids were prepared from E. coli using a QIAprep Spin miniprep kit from Qiagen according to the manufacturer’s protocol. Mobilization of plasmids into K. pneumoniae cells was performed as previously described. Genomic DNA of K. pneumoniae was extracted using the Gene Aid DNA purification kit according to the manufacturer’s instructions. DNA fragments used for cloning were extracted from agarose gels using a QIA quick gel “25849133 extraction kit from Qiagen. PCR products were purified using a QIA quick PCR purification kit and, when cloned, sequenced to confirm the correct sequences. Primers used in the present study were custom-synthesized. Construction of the cpxAR deletion mutant in K. pneumoniae strain NTUH-K2044 The MisT2 database shows the presence of.466 signaling proteins in 
the 5,472,672 bp genome sequence of the K1 serotype. The CpxAR operon is located starting from nucleotides 76799 bps to 78867 bps in the genome sequence of K. pneumoniae NTUH-K2044. To construct cpxAR knock out, a 700 bp internal fragment encompassing cpxA and cpxR of the operon was amplified by PCR using DcpxA/cpxR-F and DcpxA/cpxR-R primer from its genomic DNA. The PCR product was ligated into an EcoRI digested plasmid pUT-Km which was blunted by klenow reaction that contained the kanamycin resistance gene, transformed into E. coli S17-1l pir and the resulting recombinant plasmid harbouring the internal fragment of cpxAR was designated as pUT-Km/GR. The plasmid pUT-Km/GR was mobilized into recipient K. pneumoniae NTUH-K2044 from donor E. coli S17-1l pir. Briefly, K. pneumoniae was inoculated into 10 ml LB and was incubated for 23 h till OD600 nm reaches 0.2. For matings, recipient and donor culture were mixed in a ratio of 1:2 respectively, pelleted and spotted onto the centre of an LB agar plate. After 3 h of growth at 37uC the cells were plated on Klebsiella selective agar containing Kanamycin 100 mg/ml and 5 mg/ml chlorhexidine to select for colonies. It is expected that colonies that appear on
