As the field of nanomedicine emerges, there is a lag in research surrounding the topic of nanoparticle (NP) toxicity, particularly concerned with mechanisms of action. The continuous emergence of bacterial resistance has challenged the research community to develop novel antibiotic agents. Metal NPs are among the most promising of these because show strong antibacterial activity. This review summarizes and discusses proposed mechanisms of antibacterial action of different metal NPs. These mechanisms of bacterial killing include the production of reactive oxygen species, cation release, biomolecule damages, ATP depletion, and membrane interaction. Finally, a comprehensive analysis of the effects of NPs on the regulation of genes and proteins (transcriptomic and proteomic) profiles is discussed.

Mycobacterium tuberculosis (Mtb) pathogenicity depends on its ability to inhibit phagosome acidification and maturation processes after engulfment by macrophages. Here, we show that the secreted Mtb protein tyrosine phosphatase (PtpA) binds to subunit H of the macrophage vacuolar-H + -ATPase (V-ATPase) machinery, a multisubunit protein complex in the phagosome membrane that drives luminal acidification. Furthermore, we show that the macrophage class C vacuolar protein sorting complex, a key regulator of endosomal membrane fusion, associates with V-ATPase in phagosome maturation, suggesting a unique role for V-ATPase in coordinating phagosome-lysosome fusion. PtpA interaction with host V-ATPase is required for the previously reported dephosphorylation of VPS33B and subsequent exclusion of V-ATPase from the phagosome during Mtb infection. These findings show that inhibition of phagosome acidification in the mycobacterial phagosome is directly attributed to PtpA, a key protein needed for Mtb survival and pathogenicity within host macrophages.phagocytosis | vesicular trafficking

Entry into host macrophages and evasion of intracellular destruction mechanisms, including phagosome-lysosome fusion, are critical elements of Mycobacterium tuberculosis (Mtb) pathogenesis. To achieve this, the Mtb genome encodes several proteins that modify host signaling pathways. PtpA, a low-molecular weight tyrosine phosphatase, is a secreted Mtb protein of unknown function. The lack of tyrosine kinases in the Mtb genome suggests that PtpA may modulate host tyrosine phosphorylated protein(s). We report that a genetic deletion of ptpA attenuates Mtb growth in human macrophages, and expression of PtpA-neutralizing antibodies simulated this effect. We identify VPS33B, a regulator of membrane fusion, as a PtpA substrate. VPS33B and PtpA colocalize in Mtb-infected human macrophages. PtpA secretion combined with active-phosphorylated VPS33B inhibited phagosome-lysosome fusion, a process arrested in Mtb infections. These results demonstrate that PtpA is essential for Mtb intracellular persistence and identify a key host regulatory pathway that is inactivated by Mtb.

No abstract

SUMMARY The mechanisms by which Mycobacterium tuberculosis (Mtb) maintains metabolic equilibrium to survive during infection and upon exposure to antimycobacterial drugs are poorly characterized. Ergothioneine (EGT) and mycothiol (MSH) are the major redox buffers present in Mtb, but the contribution of EGT to Mtb redox homeostasis and virulence remains unknown. We report that Mtb WhiB3, a 4Fe-4S redox sensor protein, regulates EGT production and maintains bioenergetic homeostasis. We show that central carbon metabolism and lipid precursors regulate EGT production and that EGT modulates drug sensitivity. Notably, EGT and MSH are both essential for redox and bioenergetic homeostasis. Transcriptomic analyses of EGT and MSH mutants indicate overlapping, but distinct functions of EGT and MSH. Lastly, we show that EGT is critical for Mtb survival in both macrophages and mice. This study has uncovered a dynamic balance between Mtb redox and bioenergetic homeostasis, which critically influences Mtb drug susceptibility and pathogenicity.

Lung cancer is the leading cause of cancer-related deaths in North America and other developed countries. One of the reasons lung cancer is at the top of the list is that it is often not diagnosed until the cancer is at an advanced stage. Thus, the earliest diagnosis of lung cancer is crucial, especially in screening high-risk populations, such as smokers, exposure to fumes, oil fields, toxic occupational places, etc. Based on the current knowledge, it looks that there is an urgent need to identify novel biomarkers. The current diagnosis of lung cancer includes different types of imaging complemented with pathological assessment of biopsies, but these techniques can still not detect early lung cancer developments. In this review, we described the advantages and disadvantages of current methods used in diagnosing lung cancer, and we provide an analysis of the potential use of body fluids as carriers of biomarkers as predictors of cancer development and progression.

No abstract

Recombinant single-chain antibodies (scFvs) that are expressed in the cytoplasm of cells are of considerable biotechnological and therapeutic potential. However, the reducing environment of the cytoplasm inhibits the formation of the intradomain disul®de bonds that are essential for correct folding and functionality of these antibody fragments. Thus, scFvs expressed in the cytoplasm are mostly insoluble and inactive.Here, we describe a general approach for stabilizing scFvs for ef®cient functional expression in the cell cytoplasm in a soluble, active form. The scFvs are expressed as C-terminal fusions with the Escherichia coli maltose-binding protein (MBP). We tested a large panel of scFvs that were derived from hybridomas and from murine and human scFv phage display and expression libraries by comparing their stability and functionality as un-fused versus MBP fused proteins. We found that MBP fused scFvs are expressed at high levels in the cytoplasm of E. coli as soluble and active proteins regardless of the redox state of the bacterial cytoplasm. In contrast, most un-fused scFvs can be produced (to much lower levels) in a functional form only when expressed in trxB À but not in trxB E. coli cells. We show that MBP-scFv fusions are more stable than the corresponding un-fused scFvs, and that they perform more ef®ciently in vivo as cytoplasmic intrabodies in E. coli. Thus, MBP seems to function as a molecular chaperone that promotes the solubility and stability of scFvs that are fused to it.