The Role of the Novel Exopolyphosphatase MT0516 in Mycobacterium tuberculosis Drug Tolerance and Persistence

Inorganic polyphosphate (poly P) has been postulated to play a regulatory role in the transition to bacterial persistence. In bacteria, poly P balance in the cell is maintained by the hydrolysis activity of the exopolyphosphatase PPX. However, the Mycobacterium tuberculosis PPX has not been characterized previously. Here we show that recombinant MT0516 hydrolyzes poly P, and an MT0516-deficient M. tuberculosis mutant exhibits elevated intracellular levels of poly P and increased expression of the genes mprB, sigE, and rel relative to the isogenic wild-type strain, indicating poly P-mediated signaling. Deficiency of MT0516 resulted in decelerated growth during logarithmic-phase in axenic cultures, and tolerance to the cell wall-active drug isoniazid. The MT0516-deficient mutant showed a significant survival defect in activated human macrophages and reduced persistence in the lungs of guinea pigs. We conclude that exopolyphosphatase is required for long-term survival of M. tuberculosis in necrotic lung lesions

Mechanism of energy metabolism for adapted Acidithiobacillus ferrooxidans

This article aimed to elucidate the mechanism of energy metabolism for copper resistance in adapted Acidithiobacillus ferrooxidans. Initially, during batch cultivation process, ferrous oxidation (Fe 2+ ), bacteria growth, intracellular energy charge status, polyphosphate kinase (PPK) activiy, and inorganic polyphosphate (polyP) accumulation were compared between adapted and unadapted strains. Then, in the presence of copper stress, the dynamic changes of polyP levels and exopolyphosphatase (PPX) activity were investigated. Furthermore, accumulation of copper ions inside the cell was determined. Results showed that medium Fe 2+ was exhausted at 72 h and 96 h in batch culture adapted and unadapted A. ferrooxidans and a relatively higher total protein level, energy charge, PPK activiy, and polyP content was observed in adapted strain. As subjected to 50 mmol/L copper ion stress, intracellular polyP decreased to the lowest level at 8 h and 14 h after shift-time and corresponding PPK activiy increased to 443 and 276 U/mg protein, respectivly, in adapted and unadapted A. ferrooxidans, indicating much energy was released from polyP degradation. As a result, intracellular copper ion was kept at a very lowered level in adatped strain. It was suggested that an efficeint energy supply system existed that contributes to transporting intracelualr copper ion out of cell during active process in adapted A. ferrooxidans. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13054, 2019. © 2018 American Institute of Chemical Engineer

(1′<i>R</i>, 2′<i>S</i>, 3′<i>R</i>)-9-(2′, 3′-Dihydroxycyclopentan-1′-yl)-Adenine and −3-Deaza-Adenine: Analogues of Aristeromycin Which Exhibit Potent Antiviral Activity with Reduced Cytotoxicity

Two synthetic analogues of aristeromycin, which were shown in a separate study to be inhibitors of S-adenosylhomocysteine hydrolase and devoid of substrate activity with adenosine kinase and adenosine deaminase, were found in this study to inhibit vaccinia virus replication in murine L929 cells and to have reduced cytotoxicity compared with that of the parent compound. Aristeromycin was shown to produce cytocidal effects on murine L929 cells, whereas the synthetic analogues produced cytostatic effects on cell growth. The antiviral effects of these synthetic analogues are correlated with their ability to elevate the intracellular ratio of S-adenosylhomocysteine/ S-adenosylmethionine. These results confirm that S-adenosylhomocysteine hydrolase is the molecular target which mediates the antiviral effects of aristeromycin and that transformation of aristeromycin by cellular adenosine kinase mediates its cytocidal properties.</jats:p