Azoreductases are involved in the bioremediation by bacteria of azo dyes found in waste water. In the gut flora, they activate azo pro-drugs, which are used for treatment of inflammatory bowel disease, releasing the active component 5-aminosalycilic acid. The bacterium P. aeruginosa has three azoreductase genes, paAzoR1, paAzoR2 and paAzoR3, which as recombinant enzymes have been shown to have different substrate specificities. The mechanism of azoreduction relies upon tautomerisation of the substrate to the hydrazone form. We report here the characterization of the P. aeruginosa azoreductase enzymes, including determining their thermostability, cofactor preference and kinetic constants against a range of their favoured substrates. The expression levels of these enzymes during growth of P. aeruginosa are altered by the presence of azo substrates. It is shown that enzymes that were originally described as azoreductases, are likely to act as NADH quinone oxidoreductases. The low sequence identities observed among NAD(P)H quinone oxidoreductase and azoreductase enzymes suggests convergent evolution.
Benzoquinones ; metabolism ; Catalytic Domain ; Enzyme Stability ; Evolution, Molecular ; Flavins ; chemistry ; Hot Temperature ; Kinetics ; Mesalamine ; chemistry ; NAD ; metabolism ; NADH, NADPH Oxidoreductases ; chemistry ; NADP ; metabolism ; Osmolar Concentration ; Oxidation-Reduction ; Phenylhydrazines ; chemistry ; Phylogeny ; Protein Binding ; Pseudomonas aeruginosa ; enzymology ; Spectrophotometry, Ultraviolet

A 48-year-old woman in her 40’s with end-stage renal disease and tertiary hyperparathyroidism (HPT) presented for a rapidly progressive maxillary tumor. Initial workup was notable for elevated intact parathyroid hormone (PTH) and diffuse thickening of skull and facial bones on computed tomography, and maxillary tumor biopsy with multinucleated giant cells. She underwent subtotal parathyroidectomy (with removal of a parathyroid adenoma and 2 hyperplastic glands) and partial resection of maxillary brown tumor. The patient’s post-operative course was complicated by hungry bone syndrome, with hypocalcemia refractory to aggressive calcium repletion. Teriparatide (recombinant PTH) was utilized with rapid resolution of hypocalcemia. To our knowledge, this is the first case of maxillary brown tumor in tertiary HPT to be reported in the USA. This case also supports teriparatide as a novel therapeutic for hungry bone syndrome refractory to aggressive calcium repletion.

DNA barcoding without assessing reliability and validity causes taxonomic errors of species identification, which is responsible for disruptions of their conservation and aquaculture industry. Although DNA barcoding facilitates molecular identification and phylogenetic analysis of species, its availability in clariid catfish lineage remains uncertain. In this study, DNA barcoding was developed and validated for clariid catfish. 2,970 barcode sequences from mitochondrial cytochrome c oxidase I (COI) and cytochrome b (Cytb) genes and D-loop sequences were analyzed for 37 clariid catfish species. The highest intraspecific nearest neighbor distances were 85.47%, 98.03%, and 89.10% for COI, Cytb, and D-loop sequences, respectively. This suggests that the Cytb gene is the most appropriate for identifying clariid catfish and can serve as a standard region for DNA barcoding. A positive barcoding gap between interspecific and intraspecific sequence divergence was observed in the Cytb dataset but not in the COI and D-loop datasets. Intraspecific variation was typically less than 4.4%, whereas interspecific variation was generally more than 66.9%. However, a species complex was detected in walking catfish and significant intraspecific sequence divergence was observed in North African catfish. These findings suggest the need to focus on developing a DNA barcoding system for classifying clariid catfish properly and to validate its efficacy for a wider range of clariid catfish. With an enriched database of multiple sequences from a target species and its genus, species identification can be more accurate and biodiversity assessment of the species can be facilitated.