RESUMO
Cellular response against different heavy metal stress differs with the metal. Arsenic and chromium are heavy metals and toxic to living systems. The concentration of these metals in seawater is very low. However, due to their solubility in nature, they actively enter cells via various transport mechanisms and cause damage to the cells. Brevibacterium casei #NIOSBA88, a marine-derived, gram-positive isolate was multi-metal tolerant. Proteomic analysis of this isolate in response to arsenic and chromium resulted in the identification of total 2549 proteins, out of which 880 proteins were found to be commonly expressed at 750 mgL-1 arsenic and 100 mgL-1 chromium and in absence of both the metals. In contrast, 533, 212, and 270 proteins were found to be unique in the absence of any metal, 750 mgL-1 of arsenic and 100 mgL-1 of chromium respectively. Proteins such as antibiotic biosynthesis monooxygenase, ArsR family transcriptional regulator, cytochrome C oxidase subunit II, and thioredoxin reductase were exclusively expressed only in response to arsenic and chromium. Other proteins like superoxide dismutase, lipid hydroperoxide reductase, and thioredoxin-disulfide reductase were found to be upregulated in response to both the metals. Most of the proteins involved in the normal cell functioning were found to be downregulated. Major metabolic functions affected include amino acid metabolism, carbohydrate metabolism, translation, and energy metabolism. Peptide mass fingerprinting of Brevibacterium casei #NIOSBA88 exposed to arsenic and chromium respectively revealed the deleterious effect of these metals on the bacterium and its strategy to overcome the stress.
Assuntos
Arsênio/metabolismo , Brevibacterium/metabolismo , Cromo/metabolismo , Proteômica , Proteínas de Bactérias/isolamento & purificação , Brevibacterium/efeitos dos fármacosRESUMO
Since enzymatic degradation is a mechanism or component of the aggressiveness of a pathogen, enzymatic activities from a Fusarium graminearum isolate obtained from infected wheat spikes of Argentina Pampa region were studied in order to understand the disease progression, tending to help disease control. In particular, the significance of the study of polygalacturonase activity is based on that such activity is produced in the early stages of infection on the host, suggesting a crucial role in the establishment of disease. In this sense, polygalacturonase activity produced by this microorganism has been purified 375 times from 2-day-old culture filtrates by gel filtration and ion-exchange chromatography successively. The purified sample showed two protein bands in sodium dodecyl sulfate-polyacrylamide gels, with a molecular mass of 40 and 55 kDa. The protein bands were identified as an endopolygalacturonase and as a serine carboxypeptidase of F. graminearum, respectively, by peptide mass fingerprinting (matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF/TOF) fragment ion analysis). The pattern of substrate degradation analyzed by thin layer chromatography confirmed the mode of action of the enzyme as an endopolygalacturonase. High activity of the polygalacturonase against polygalacturonic acid was observed between 4 and 6 of pH, and between 30 and 50 °C, being 5 and 50 °C the optimum pH and temperature, respectively. The enzyme was fully stable at pH 5 for 120 min and 30 °C and sensible to the presence of some metal ions. This information would contribute to understand the most favorable environmental conditions for establishment of the disease.