Mining of the Novel Virulent ATP-Binding Cassette Importers in Mycobacterium abscessus by Comparative Genomic Strategy.

Background: The virulent ATP-binding cassette (ABC) importers from Mycobacterium abscessus, the most common native multidrug resistant and emerging opportunistic pathogen in rapidly growing NTM, were explored by comparative genomic study, in view of the fact that the ABC importers of Mycobacterium tuberculosis, responsible for uptaking metals, anions, amino acids, peptides, sugars, and other crucial substances from the host, had been proved to be closely related with the bacillus's virulence, survival in the host macrophages, antibiotic resistance, modulation of host immune system, and so on, although detailed mechanism was unclear. Methods: For virulent ABC importers from M. abscessus predicted by orthology and phylogeny analysis of nucleotide-binding domains (NBDs) of Mycobacterium smegmatis, M. abscessus, and M. tuberculosis, the antibiotic susceptibility of overexpression transformant and knockout mutant was assayed after confirmation by in vitro experiment. Results: Three-domain importers were dominant ones in M. abscessus (60.0%), four-domain ones dominant in M. tuberculosis (87.5%), whereas both types were same in M. smegmatis (41.9%). In the phylogenetic tree, the importers of M. abscessus (53.3%) and M. tuberculosis (62.5%) were mainly distributed in clay A, whereas the clay E was exclusively composed of M. smegmatis NBDs, which hinted possible reprogramming of the transporter system during the pathogen evolution. In clay A, MAB_2178 and others were predicted virulence-associated because of high sequence similarity to M. tuberculosis virulence importers. Conclusions: The importance and complexity of antibiotics resistance mechanisms of MAB_2176-2177-2178 were pointed out by its overexpression enhancing bacterial resistance to ciprofloxacin, clarithromycin, cefoxitin, and sensitivity to amikacin, and knockout having opposite phenotypes.

Identification of peptide biomarkers for authentication of Atlantic salmon and rainbow trout with untargeted and targeted proteomics approaches and quantitative detection of adulteration.

Atlantic salmon is often adulterated or substituted by rainbow trout with much lower price and quality. However, it is extremely difficult to distinguish Atlantic salmon and rainbow trout due to their similar appearance and close relationship in species. In the present work, untargeted and targeted proteomics approaches were both implemented to identify species-specific peptide biomarkers of Atlantic salmon and rainbow trout. Potential peptide biomarkers were obtained through matching HRMS data with UniProt database, screened by BLAST and then verified with real samples. Five peptide biomarkers were identified each for Atlantic salmon and rainbow trout. MRM method was established for quantitative measurement of rainbow trout Adulteration in Atlantic salmon, showing high sensitivity and repeatability. The biomarker peptide GDPGPGGPQGEQGVVGPAGISGDK was used for quantification. The limit of the detection (LOD) of adulteration of rainbow trout is 0.19%, and the limit of quantitation (LOQ) is 0.62%. Furthermore, this method was successfully applied to analyze a number of Atlantic salmon and Rainbow trout samples from different regions and different batches, as well as commercially available processed products.