Revealing the Functions of the Transketolase Enzyme Isoforms in Rhodopseudomonas palustris Using a Systems Biology Approach

BACKGROUND: Rhodopseudomonas palustris (R. palustris) is a purple non-sulfur anoxygenic phototrophic bacterium that belongs to the class of proteobacteria. It is capable of absorbing atmospheric carbon dioxide and converting it to biomass via the process of photosynthesis and the Calvin-Benson-Bassham (CBB) cycle. Transketolase is a key enzyme involved in the CBB cycle. Here, we reveal the functions of transketolase isoforms I and II in R. palustris using a systems biology approach. METHODOLOGY/PRINCIPAL FINDINGS: By measuring growth ability, we found that transketolase could enhance the autotrophic growth and biomass production of R. palustris. Microarray and real-time quantitative PCR revealed that transketolase isoforms I and II were involved in different carbon metabolic pathways. In addition, immunogold staining demonstrated that the two transketolase isoforms had different spatial localizations: transketolase I was primarily associated with the intracytoplasmic membrane (ICM) but transketolase II was mostly distributed in the cytoplasm. Comparative proteomic analysis and network construction of transketolase over-expression and negative control (NC) strains revealed that protein folding, transcriptional regulation, amino acid transport and CBB cycle-associated carbon metabolism were enriched in the transketolase I over-expressed strain. In contrast, ATP synthesis, carbohydrate transport, glycolysis-associated carbon metabolism and CBB cycle-associated carbon metabolism were enriched in the transketolase II over-expressed strain. Furthermore, ATP synthesis assays showed a significant increase in ATP synthesis in the transketolase II over-expressed strain. A PEPCK activity assay showed that PEPCK activity was higher in transketolase over-expressed strains than in the negative control strain. CONCLUSIONS/SIGNIFICANCE: Taken together, our results indicate that the two isoforms of transketolase in R. palustris could affect photoautotrophic growth through both common and divergent metabolic mechanisms

Urethroplasty with dorsal buccal mucosa graft. Is it still the method of choice in long term urethral stenosis?

The aim of our work was to evaluate the long-term changes in symptoms (median 42 months) and to analyze data for any negative predictive factors for the application of the procedure, in patients who underwent to urethroplasty with dorsal buccal mucosa graft. During the period from 2010 to 2015 27 patients were examined. Than they underwent urethroplasty using dorsal buccal mucosa graft (graft of 4 x 2.5 cm). The evaluation of symptoms has been addressed through the application of the IPSS Quality of Life Questionnaire (International Prostatic Symptoms Score) and the evaluation of urinary flow has been carried out by a comparative analysis between the pre- and post-operative uroflowmetry. As our study has shown, data obtained by the screening tests in the post-operative follow-up indicate that there is an increase in the maximum flow of urine until 1 month after surgery. The results in the long-term follow-up are different because they show a partial reduction of the maximum flow although it is maintained around an average value of 23 ml/s being still higher than the maximum flow in the pre- operative period. According to our results it follows that there is a low failure rate of the procedure after a median of 42 months. Only in patients with urethral stenosis longer than 2 cm, a lower long term success is achieved. From what we could observe, this length of the stenosis seems to be the only negative predictive factor for long-term maintenance of a good Quality of Life in patients undergoing the procedure. The results obtained from our study confirm literature data according to which, the gold standard for 2-cm long bulbar urethral stricture whose lumen is well preserved with circumferential spongiofibrosis limited to 1-2 mm is the dorsal graft urethroplasty with buccal mucosa that in our study showed success rates higher of 80% after a median follow up of 42 months and a percentage of relapse-free patients of 82.1% (median 3.5 years)

Chemotaxis of Pseudomonas putida toward chlorinated benzoates.

The chlorinated aromatic acids 3-chlorobenzoate and 4-chlorobenzoate are chemoattractants for Pseudomonas putida PRS2000. These compounds are detected by a chromosomally encoded chemotactic response to benzoate which is inducible by beta-ketoadipate, an intermediate of benzoate catabolism. Plasmid pAC27, encoding enzymes for 3-chlorobenzoate degradation, does not appear to carry genes for chemotaxis toward chlorinated compounds