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Wendlandt S.,Institute of Farm Animal Genetics | Shen J.,China Agricultural University | Kadlec K.,Institute of Farm Animal Genetics | Wang Y.,China Agricultural University | And 5 more authors.
Trends in Microbiology | Year: 2015

Most antimicrobial resistance genes known so far to occur in staphylococci of animal origin confer resistance to a specific class of antimicrobial agents or to selected members within such a class. However, there are also a few examples of multidrug resistance (MDR) genes that confer resistance to antimicrobial agents of different classes by either target site methylation or active efflux via ATP-binding cassette (ABC) transporters. The present review provides an overview of these MDR genes with particular reference to those genes involved in resistance to critically or highly important antimicrobial agents used in human and veterinary medicine. Moreover, their location on mobile genetic elements and colocated resistance genes, which may play a role in coselection and persistence of the MDR genes, are addressed. © 2014 Elsevier Ltd.

Zhang W.-J.,Chinese Academy of Agriculture | Xu X.-R.,Southwest University | Schwarz S.,Institute of Farm Animal Genetics | Wang X.-M.,Chinese Academy of Agriculture | And 3 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2014

Objectives: To determine the complete nucleotide sequence of the multidrug resistance plasmid pSCEC2, isolated from a porcine Escherichia coli strain, and to analyse it with particular reference to the cfr gene region. Methods: Plasmid pSCEC2 was purified from its E. coli J53 transconjugant and then sequenced using the 454 GS-FLX System. After draft assembly, predicted gaps were closed by PCR with subsequent sequencing of the amplicons. Results: Plasmid pSCEC2 is 135 615 bp in size and contains 200 open reading frames for proteins of ≥100 amino acids. Analysis of the sequence of pSCEC2 revealed two resistance gene segments. The 4.4 kb cfr-containing segment is flanked by two IS256 elements in the same orientation, which are believed to be involved in the dissemination of the rRNA methylase gene cfr. The other segment harbours the resistance genes floR, tet(A)-tetR, strA/strB and sul2, which have previously been found on other IncA/C plasmids. Except for these two resistance gene regions, the pSCEC2 backbone displayed >99% nucleotide sequence identity to that of other IncA/C family plasmids isolated in France, Chile and the USA. Conclusions: The cfr gene was identified on an IncA/C plasmid, which is well known for its broad host range and transfer and maintenance properties. The location on such a plasmid will further accelerate the dissemination of cfr and co-located resistance genes among different Gram-negative bacteria. The genetic context of cfr on plasmid pSCEC2 underlines the complexity of cfr transfer events and confirms the role that insertion sequences play in the spread of cfr. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

Xu L.,Tsinghua University | Xu L.,Chinese Academy of Agriculture | Guo J.,Tsinghua University | Zheng X.,Tsinghua University | And 4 more authors.
Acta Crystallographica Section F: Structural Biology and Crystallization Communications | Year: 2010

The Rv0045c protein is predicted to be an esterase that is involved in lipid metabolism in Mycobacterium tuberculosis. The protein was overproduced in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The Rv0045c protein crystals diffracted to a resolution of 2.7 Å using a synchrotron-radiation source and belonged to space group P31 or P32, with unit-cell parameters a = b = 73.465, c = 48.064 Å, = Β = 90, = 120°. Purified SeMet-labelled Rv0045c protein was also crystallized and formed crystals that diffracted to a resolution of 3.0 Å using an in-house X-ray radiation source. © 2010 International Union of Crystallography. All rights reserved.

Zheng X.,Tsinghua University | Zheng X.,Chinese Academy of Agriculture | Guo J.,Tsinghua University | Guo J.,Chinese Academy of Agriculture | And 8 more authors.
PLoS ONE | Year: 2011

There are at least 250 enzymes in Mycobacterium tuberculosis (M. tuberculosis) involved in lipid metabolism. Some of the enzymes are required for bacterial survival and full virulence. The esterase Rv0045c shares little amino acid sequence similarity with other members of the esterase/lipase family. Here, we report the 3D structure of Rv0045c. Our studies demonstrated that Rv0045c is a novel member of α/β hydrolase fold family. The structure of esterase Rv0045c contains two distinct domains: the α/β fold domain and the cap domain. The active site of esterase Rv0045c is highly conserved and comprised of two residues: Ser154 and His309. We proposed that Rv0045c probably employs two kinds of enzymatic mechanisms when hydrolyzing C-O ester bonds within substrates. The structure provides insight into the hydrolysis mechanism of the C-O ester bond, and will be helpful in understanding the ester/lipid metabolism in M. tuberculosis. © 2011 Zheng et al.

Guo J.,Tsinghua University | Guo J.,Chinese Academy of Agriculture | Zheng X.,Tsinghua University | Xu L.,Tsinghua University | And 6 more authors.
PLoS ONE | Year: 2010

Background: It was proposed that there are at least 250 enzymes in M. tuberculosis involved in lipid metabolism. Rv0045c was predicted to be a hydrolase by amino acid sequence similarity, although its precise biochemical characterization and function remained to be defined. Methodology/Principal Findings: We expressed the Rv0045c protein to high levels in E. coli and purified the protein to high purity. We confirmed that the prepared protein was the Rv0045c protein by mass spectrometry analysis. Circular dichroism spectroscopy analysis showed that the protein possessed abundant β-sheet secondary structure, and confirmed that its conformation was stable in the range pH 6.0-10.0 and at temperatures ≤40°C. Enzyme activity analysis indicated that the Rv0045c protein could efficiently hydrolyze short chain p-nitrophenyl esters (C2-C8), and its suitable substrate was pnitrophenyl caproate (C6) with optimal catalytic conditions of 39°C and pH 8.0. Conclusions/Significance: Our results demonstrated that the Rv0045c protein is a novel esterase. These experiments will be helpful in understanding ester/lipid metabolism related to M. tuberculosis. © 2010 Guo et al.

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