RESUMO
Enterococcus is one of the most controversial genera belonging to Lactic Acid Bacteria. Research involving this microorganism reflects its dual behavior as regards its safety. Although it has also been associated to nosocomial infections, natural occurrence of Enterococcus faecium in food contributes to the final quality of cheese. This bacterium is capable of fermenting citrate, which is metabolized to pyruvate and finally derives in the production of the aroma compounds diacetyl, acetoin and 2,3 butanediol. Citrate metabolism was studied in E. faecium but no data about genes related to these pathways have been described. A bioinformatic approach allowed us to differentiate cit(-) (no citrate metabolism genes) from cit(+) strains in E. faecium. Furthermore, we could classify them according to genes encoding for the transcriptional regulator, the oxaloacetate decarboxylase and the citrate transporter. Thus we defined type I organization having CitI regulator (DeoR family), CitM cytoplasmic soluble oxaloacetate decarboxylase (Malic Enzyme family) and CitP citrate transporter (2-hydroxy-carboxylate transporter family) and type II organization with CitO regulator (GntR family), OAD membrane oxaloacetate decarboxylase complex (Na(+)-transport decarboxylase enzyme family) and CitH citrate transporter (CitMHS family). We isolated and identified 17 E. faecium strains from regional cheeses. PCR analyses allowed us to classify them as cit(-) or cit(+). Within the latter classification we could differentiate type I but no type II organization. Remarkably, we came upon E. faecium GM75 strain which carries the insertion sequence IS256, involved in adaptative and evolution processes of bacteria related to Staphylococcus and Enterococcus genera. In this work we describe the differential behavior in citrate transport, metabolism and aroma generation of three strains and we present results that link citrate metabolism and genetic organizations in E. faecium for the first time.
Assuntos
Queijo/microbiologia , Ácido Cítrico/metabolismo , Elementos de DNA Transponíveis/genética , Enterococcus faecium/genética , Enterococcus faecium/metabolismo , Acetoína/metabolismo , Sequência de Bases , Transporte Biológico/genética , Carboxiliases/genética , Carboxiliases/metabolismo , Proteínas de Transporte/genética , Diacetil/metabolismo , Enterococcus faecium/isolamento & purificação , Fermentação/fisiologia , Microbiologia de Alimentos , Malato Desidrogenase/genética , Dados de Sequência Molecular , Complexos Multienzimáticos/metabolismo , Família Multigênica , Oxo-Ácido-Liases/metabolismoRESUMO
Despite major advances in pharmacologic therapy over the last few decades, dyslipidemia remains a prevalent, insufficiently recognized, and undercontrolled risk factor for cardiovascular disease. Statins are the mainstay of hypercholesterolemia treatment, but because of adherence and tolerability issues that limit dose titration, there is a need for additional therapies with good efficacy and better tolerability. Adenosine triphosphate (ATP) citrate lyase, a cytoplasmic enzyme responsible for the generation of acetyl coenzyme A for the de novo synthesis of fatty acids and cholesterol, is a very interesting molecular target for the reduction of plasma lipids. Furthermore, ATP citrate lyase inhibition may be accompanied by activation of 5'-adenosine monophosphate-activated protein kinase, a key signaling molecule that acts a central hub in cellular metabolic regulation. ETC-1002 is a small molecule inhibitor of ATP citrate lyase that also activates 5'-adenosine monophosphate-activated protein kinase, effectively reducing low-density lipoprotein cholesterol and inducing some other positive metabolic changes. Recent evidence from phase I and II clinical trials in humans has shown a positive efficacy and safety profile of ETC-1002, with low-density lipoprotein cholesterol reductions similar to those attainable by usual doses of many statins and with no major apparent side effects. These results potentially introduce a new family of medications that may expand our therapeutic arsenal against hypercholesterolemia.