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Volume 195, no. 16, p. 35143523, 2013. A number of problems related to images published in this paper have been brought to our attention. Figure 1D contains duplicated images in lanes S and LE, and Fig. 4D and 6B contain images previously published in articles in this journal and in Microbiology and Microbial Pathogenesis, i.e., the following: C. G. Ramos, S. A. Sousa, A. M. Grilo, J. R. Feliciano, and J. H. Leitão, J. Bacteriol. 193:15151526, 2011. doi:10.1128/JB.01374-11. S. A. Sousa, C. G. Ramos, L. M. Moreira, and J. H. Leitão, Microbiology 156:896908, 2010. doi:10.1099/mic.0.035139-0. C. G. Ramos, S. A. Sousa, A. M. Grilo, L. Eberl, and J. H. Leitão, Microb. Pathog. 48:168177, 2010. doi: 10.1016/j.micpath.2010.02.006. Therefore, we retract the paper. We deeply regret this situation and apologize for any inconvenience to the editors and readers of Journal of Bacteriology, Microbial Pathogenesis, and Microbiology.
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Small non-coding RNAs (sRNAs) are important players of gene expression regulation in bacterial pathogens. MtvR is a 136-nucleotide long sRNA previously identified in the human pathogen Burkholderia cenocepacia J2315 and with homologues restricted to bacteria of the Burkholderia cepacia complex. In this work we have investigated the effects of expressing MtvR in Escherichia coli and Pseudomonas aeruginosa. Results are presented showing that MtvR negatively regulates the hfq mRNA levels in both bacterial species. In the case of E. coli, this negative regulation is shown to involve binding of MtvR to the 5'-UTR region of the hfqEc mRNA. Results presented also show that expression of MtvR in E. coli and P. aeruginosa originates multiple phenotypes, including reduced resistance to selected stresses, biofilm formation ability, and increased susceptibility to various antibiotics.
Assuntos
Burkholderia cenocepacia/genética , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Fator Proteico 1 do Hospedeiro/genética , Pseudomonas aeruginosa/genética , RNA Mensageiro/genética , Pequeno RNA não Traduzido/genética , Regiões 5' não Traduzidas , Pareamento de Bases , Sequência de Bases , Biofilmes , Farmacorresistência Bacteriana/genética , Epistasia Genética , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Fator Proteico 1 do Hospedeiro/metabolismo , Viabilidade Microbiana/genética , Dados de Sequência Molecular , Biossíntese de Proteínas , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/metabolismo , Estabilidade de RNA , RNA Mensageiro/química , Pequeno RNA não Traduzido/química , Estresse FisiológicoRESUMO
Burkholderia cenocepacia J2315 is a highly epidemic and transmissible clinical isolate of the Burkholderia cepacia complex (Bcc), a group of bacteria causing life-threatening respiratory infections among cystic fibrosis patients. This work describes the functional analysis of the 136-nucleotide (nt)-long MtvR small noncoding RNA (sRNA) from the Bcc member B. cenocepacia J2315, with homologues restricted to the genus Burkholderia. Bioinformatic target predictions revealed a total of 309 mRNAs to be putative MtvR targets. The mRNA levels corresponding to 17 of 19 selected genes were found to be affected when MtvR was either overexpressed or silenced. Analysis of the interaction between MtvR and the hfq mRNA, one of its targets, showed that the sRNA binds exclusively to the 5' untranslated region (UTR) of the hfq mRNA. This interaction resulted in decreased protein synthesis, suggesting a negative regulatory effect of MtvR on the RNA chaperone Hfq. Bacterial strains with MtvR silenced or overexpressed exhibited pleiotropic phenotypes related to growth and survival after several stresses, swimming and swarming motilities, biofilm formation, resistance to antibiotics, and ability to colonize and kill the nematode Caenorhabditis elegans. Together, the results indicate that the MtvR sRNA is a major posttranscriptional regulator in B. cenocepacia.
Assuntos
Burkholderia cenocepacia/metabolismo , RNA Bacteriano/metabolismo , RNA não Traduzido/metabolismo , Antibacterianos/farmacologia , Biofilmes , Burkholderia cenocepacia/efeitos dos fármacos , Burkholderia cenocepacia/genética , DNA Bacteriano/genética , Farmacorresistência Bacteriana , Regulação Bacteriana da Expressão Gênica , RNA Bacteriano/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA não Traduzido/genética , Estresse FisiológicoRESUMO
Small non-coding regulatory RNAs (sRNAs) play important roles in regulating gene expression at the post-transcriptional level and often require the RNA chaperone Hfq. The human opportunistic pathogen Burkholderia cenocepacia J2315 encodes two distinct RNA chaperones, Hfq and Hfq2. The present work describes the experimental identification and validation of 24 sRNAs from B. cenocepacia J2315, based on the co-purification of sRNAs with the bacterium Hfq protein, followed by conversion into cDNA, cloning, computational analysis of sequences and validation by Northern blot analysis. The sRNAs here reported escaped identification by previous studies based on transcriptomics or bioinformatic analyses. Results presented indicate that 3 sRNAs are exclusive to bacteria of the Burkholderia cepacia complex and have no homologues in other bacteria, while the other 21 share homology, at different extents, to sRNAs of other bacterial species.
Assuntos
Burkholderia cenocepacia/genética , RNA Bacteriano/genética , Pequeno RNA não Traduzido/genética , Sequência de Bases , Clonagem Molecular , Biologia Computacional , Dados de Sequência Molecular , Análise de Sequência de RNA , Homologia de Sequência do Ácido NucleicoRESUMO
Small non-coding regulatory RNAs (sRNAs) post-transcriptionally affect multiple phenotypes in prokaryotes and eukaryotes, yet most of the underlying regulatory mechanisms and the nature of the target mRNAs remain unclear. Here we report the identification and functional analysis of the novel cis-encoded sRNA h2cR, from the human opportunistic pathogen Burkholderia cenocepacia J2315. The sRNA was found to negatively regulate the hfq2 mRNA, through binding to part of the 5'-UTR region of the hfq2 mRNA, resulting in accelerated hfq2 mRNA decay and reduced protein levels in exponentially growing cells. Both the h2cR transcript and the hfq2 mRNA are stabilized by the other B. cenocepacia RNA chaperone, Hfq. Infection experiments using the nematode Caenorhabditis elegans revealed that down-regulation of Hfq2 by h2cR decreases the B. cenocepacia ability to colonize and persist within the nematode, suggesting a role for h2cR on bacterial persistence in the host.