RESUMEN
Quorum sensing is a cell-cell signaling mechanism based on cell density and that involves the production of hormone-like molecules called autoinducers (AI). One of the most studied AIs has been termed AI-2, and its biosynthesis requires the enzyme encoded by luxS. We have previously described for the first time that Bacteroides species can produce molecules with AI-2 activity. In this study, we focus on the detection of luxS and its activity as the AI-2 synthase in Bacteroides species. The strains Bacteroides fragilis B3b and Bacteroides vulgatus ATCC 8482 were selected based on a positive phenotype for AI-2 production and the presence of a putative luxS in the genome, respectively. In order to identify the luxS gene, cloning and heterologous expression strategies were utilized. We demonstrate that both strains contain functional luxS orthologs that can complement AI-2 production in Escherichia coli.
Asunto(s)
Proteínas Bacterianas/genética , Bacteroides fragilis/genética , Bacteroides/genética , Biopelículas/crecimiento & desarrollo , Liasas de Carbono-Azufre/genética , Regulación Bacteriana de la Expresión Génica , Homoserina/análogos & derivados , Secuencia de Aminoácidos , Proteínas Bacterianas/metabolismo , Bacteroides/metabolismo , Bacteroides fragilis/metabolismo , Liasas de Carbono-Azufre/metabolismo , Secuencia Conservada , Escherichia coli/genética , Escherichia coli/metabolismo , Prueba de Complementación Genética , Homoserina/biosíntesis , Lactonas , Datos de Secuencia Molecular , Percepción de Quorum , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Transducción de SeñalRESUMEN
INTRODUCTION: Bartonella infection in cats can represent a risk to owners, particularly today when considering the increase in cat populations and their role in human bartonellosis epidemiology. In the present study, we aimed to detect Bartonella spp. in blood samples from 163 asymptomatic privately-owned cats from the metropolitan area of Rio de Janeiro State, Brazil by using a conventional PCR test and also to evaluate the association between Bartonella spp. and hematological changes in positive cats. METHODOLOGY: PCR assays were performed targeting the Bartonella spp heat shock protein (htrA) gene and complete blood counts were also performed in all samples. Positive PCR samples were confirmed by the presence of two genes, citrate synthase (gltA) and RNA polymerase beta-subunit-encoding (rpoB). RESULTS: A total of 74.85% (122/163) of the tested cats were positive for Bartonella spp and partial sequencing confirmed to be B. henselae. All hematological findings from the 163 cats tested (PCR-positive and negative), presented normal limits. CONCLUSIONS: This study demonstrates that B. henselae is present in almost 75% asymptomatic privately-owned domestic cats in the metropolitan region of Rio de Janeiro State, Brazil. Our results also show that hematological findings in Bartonella spp. infected cats are uncommon. In this scenario, the use of PCR as a diagnostic tool in feline Bartonella infections should be considered. Finally, these results also demonstrate the potential risk of Bartonella spp. infection in the human population of the metropolitan area of Rio de Janeiro State, Brazil.
RESUMEN
Quorum sensing is a density-dependent gene regulation mechanism that has been described in many bacterial species in the last decades. Bacteria that use quorum sensing as part of their gene regulation circuits produce molecules called autoinducers that accumulate in the environment and activate target genes in a quorum-dependent way. Some specific clues led us to hypothesize that Bacteroides species can produce autoinducers and possess a quorum sensing system. First, Bacteroides are anaerobic bacteria that are frequently involved in polymicrobial infections. These infections often involve Pseudomonas aeruginosa and Staphylococcus aureus, two of the best understood examples of bacteria that employ quorum sensing systems as part of their pathogenesis. Also, studies have detected the presence of a quorum sensing gene involved in the production of autoinducers in Porphyromonas gingivalis, a species closely related to the Bacteroides genus. These and other evidences prompted us to investigate if Bacteroides strains could produce autoinducer molecules that could be detected by a Vibrio harveyi reporter system. In this paper, we show that supernatants of B. fragilis, B. vulgatus and B. distasonis strains are able to stimulate the V. harveyi quorum sensing system 2. Also, we were able to demonstrate that the stimulation detected is due to the production of autoinducer molecules and not the growth of reporter strains after addition of supernatant. Moreover, the phenomenon observed does not seem to represent the degradation of repressors possibly present in the culture medium used. We could also amplify bands from some of the strains tested using primers designed to the luxS gene of Escherichia coli. Altogether, our results show that B. fragilis, B. vulgatus and B. distasonis (but possibly some other species) can produce V. harveyi autoinducer 2-related molecules. However, the role of such molecules in the biology of these organisms remains unknown.