66 research outputs found
Metalloadsorption by Escherichia coli cells displaying yeast and mammalian metallothioneins anchored to the outer membrane protein LamB
Yeast (CUP1) and mammalian (HMT-1A) metallothioneins (MTs) have been efficiently expressed in Escherichia
coli as fusions to the outer membrane protein LamB. A 65-amino-acid sequence from the CUP1 protein
of Saccharomyces cerevisiae (yeast [Y] MT) was genetically inserted in permissive site 153 of the LamB sequence,
which faces the outer medium. A second LamB fusion at position 153 was created with 66 amino acids
recruited from the form of human (H) MT that is predominant in the adipose tissue, HMT-1A. Both LamB153-
YMT and LamB153-HMT hybrids were produced in vivo as full-length proteins, without any indication of instability
or proteolytic degradation. Each of the two fusion proteins was functional as the port of entry of lambda
phage variants, suggesting maintenance of the overall topology of the wild-type LamB. Expression of the
hybrid proteins in vivo multiplied the natural ability of E. coli cells to bind Cd21 15- to 20-fold, in good correlation
with the number of metal-binding centers contributed by the MT moiety of the fusion
HIV-1 protease-induced apoptosis
BACKGROUND: Apoptosis is one of the presumptive causes of CD4(+) T cell depletion during HIV infection and progression to AIDS. However, the precise role of HIV-1 in this process remains unexplained. HIV-1 protease (PR) has been suggested as a possible factor, but a direct link between HIV-1 PR enzymatic activity and apoptosis has not been established. RESULTS: Here, we show that expression of active HIV-1 PR induces death in HeLa and HEK-293 cells via the mitochondrial apoptotic pathway. This conclusion is based on in vivo observations of the direct localization of HIV-1 PR in mitochondria, a key player in triggering apoptosis. Moreover, we observed an HIV-1 PR concentration-dependent decrease in mitochondrial membrane potential and the role of HIV-1 PR in activation of caspase 9, PARP cleavage and DNA fragmentation. In addition, in vitro data demonstrated that HIV-1 PR mediates cleavage of mitochondrial proteins Tom22, VDAC and ANT, leading to release of AIF and Hsp60 proteins. By using yeast two-hybrid screening, we also identified a new HIV-1 PR interaction partner, breast carcinoma-associated protein 3 (BCA3). We found that BCA3 accelerates p53 transcriptional activity on the bax promoter, thus elevating the cellular level of pro-apoptotic Bax protein. CONCLUSION: In summary, our results describe the involvement of HIV-1 PR in apoptosis, which is caused either by a direct effect of HIV-1 PR on mitochondrial membrane integrity or by its interaction with cellular protein BCA3
Chemical Microrobots as Self-Propelled Microbrushes against Dental Biofilm
Mouths offer the perfect environments for microbial cell formation, promoting the growth of biofilms, for example, on teeth. Dental biofilm exhibits strong resistance to antibiotics and is a cause of many dental diseases. Common strategies for dental biofilm removal involve the addition of high concentrations of hydrogen peroxide (H2O2), which increases tooth sensitivity, or mechanical procedures. Here, we report a different approach based on self-propelled micromachines with high antibacterial activity for the degradation of dental biofilm. Such microrobots use low concentrations of fuel for their propulsion, and they achieve an efficient dental biofilm disruption in only 5 min of treatment. Moreover, these microrobots are biocompatible with epidermal and organ cells and may stimulate the immune system to fight against microbial infection. This approach of exploiting the active motion of bubble-propelled catalytic micromachines for oral biofilm disruption may open the door for more efficient and sophisticated treatments in dentistry
Swarming magnetic microrobots for pathogen isolation from milk
Bovine mastitis produced by Staphylococcus aureus (S. aureus) causes major problems in milk production due to the staphylococcal enterotoxins produced by this bacterium. These enterotoxins are stable and cannot be eradicated easily by common hygienic procedures once they are formed in dairy products. Here, magnetic microrobots (MagRobots) are developed based on paramagnetic hybrid microstructures loaded with IgG from rabbit serum that can bind and isolate S. aureus from milk in a concentration of 3.42 10(4) CFU g(-1) (allowable minimum level established by the United States Food and Drug Administration, FDA). Protein A, which is present on the cell wall of S. aureus, selectively binds IgG from rabbit serum and loads the bacteria onto the surface of the MagRobots. The selective isolation of S. aureus is confirmed using a mixed suspension of S. aureus and Escherichia coli (E. coli). Moreover, this fuel-free system based on magnetic robots does not affect the natural milk microbiota or add any toxic compound resulting from fuel catalysis. This system can be used to isolate and transport efficiently S. aureus and discriminate it from nontarget bacteria for subsequent identification. Finally, this system can be scaled up for industrial use in food production.Web of Scienc
Multimodal-driven magnetic microrobots with enhanced bactericidal activity for biofilm eradication and removal from titanium mesh
Modern micro/nanorobots can perform multiple tasks for biomedical and
environmental applications. Particularly, magnetic microrobots can be
completely controlled by a rotating magnetic field and their motion powered
and controlled without the use of toxic fuels, which makes them most
promising for biomedical application. Moreover, they are able to form
swarms, allowing them to perform specific tasks at a larger scale than a single
microrobot. In this work, they developed magnetic microrobots composed of
halloysite nanotubes as backbone and iron oxide (Fe3O4) nanoparticles as
magnetic material allowing magnetic propulsion and covered these with
polyethylenimine to load ampicillin and prevent the microrobots from
disassembling. These microrobots exhibit multimodal motion as single robots
as well as in swarms. In addition, they can transform from tumbling to
spinning motion and vice-versa, and when in swarm mode they can change
their motion from vortex to ribbon and back again. Finally, the vortex motion
mode is used to penetrate and disrupt the extracellular matrix of
Staphylococcus aureus biofilm colonized on titanium mesh used for bone
restoration, which improves the effect of the antibiotic’s activity. Such
magnetic microrobots for biofilm removal from medical implants could
reduce implant rejection and improve patients’ well-being.Web of Science352
Swarming Aqua Sperm Micromotors for Active Bacterial Biofilms Removal in Confined Spaces
Microscale self-propelled robots show great promise in the biomedical field and are the focus of many researchers. These tiny devices, which move and navigate by themselves, are typically based on inorganic microstructures that are not biodegradable and potentially toxic, often using toxic fuels or elaborate external energy sources, which limits their real-world applications. One potential solution to these issues is to go back to nature. Here, the authors use high-speed Aqua Sperm micromotors obtained from North African catfish (Clarias gariepinus, B. 1822) to destroy bacterial biofilm. These Aqua Sperm micromotors use water-induced dynein ATPase catalyzed adenosine triphosphate (ATP) degradation as biocompatible fuel to trigger their fast speed and snake-like undulatory locomotion that facilitate biofilm destruction in less than one minute. This efficient biofilm destruction is due to the ultra-fast velocity as well as the head size of Aqua Sperm micromotors being similar to bacteria, which facilitates their entry to and navigation within the biofilm matrix. In addition, the authors demonstrate the real-world application of Aqua Sperm micromotors by destroying biofilms that had colonized medical and laboratory tubing. The implemented system extends the biomedical application of Aqua Sperm micromotors to include hybrid robots for fertilization or cargo tasks
- …