Browsing by Subject "HSP60"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Dual-targeting GroEL/ES chaperonin and protein tyrosine phosphatase B (PtpB) inhibitors: A polypharmacology strategy for treating Mycobacterium tuberculosis infections
    (Elsevier, 2019-07-01) Washburn, Alex; Abdeen, Sanofar; Ovechkina, Yulia; Ray, Anne-Marie; Stevens, Mckayla; Chitre, Siddhi; Sivinski, Jared; Park, Yangshin; Johnson, James; Hoang; Hoang, Quyen Q.; Chapman, Eli; Parish, Tanya; Johnson, Steven M.; Biochemistry and Molecular Biology, School of Medicine
    Current treatments for Mycobacterium tuberculosis infections require long and complicated regimens that can lead to patient non-compliance, increasing incidences of antibiotic-resistant strains, and lack of efficacy against latent stages of disease. Thus, new therapeutics are needed to improve tuberculosis standard of care. One strategy is to target protein homeostasis pathways by inhibiting molecular chaperones such as GroEL/ES (HSP60/10) chaperonin systems. M. tuberculosis has two GroEL homologs: GroEL1 is not essential but is important for cytokine-dependent granuloma formation, while GroEL2 is essential for survival and likely functions as the canonical housekeeping chaperonin for folding proteins. Another strategy is to target the protein tyrosine phosphatase B (PtpB) virulence factor that M. tuberculosis secretes into host cells to help evade immune responses. In the present study, we have identified a series of GroEL/ES inhibitors that inhibit M. tuberculosis growth in liquid culture and biochemical function of PtpB in vitro. With further optimization, such dual-targeting GroEL/ES and PtpB inhibitors could be effective against all stages of tuberculosis – actively replicating bacteria, bacteria evading host cell immune responses, and granuloma formation in latent disease – which would be a significant advance to augment current therapeutics that primarily target actively replicating bacteria.
  • Thumbnail Image
    Item
    Exploring Dual-Targeting GroEL/ES & PtpB Inhibitors as a New Antibiotic Strategy for Tuberculosis
    (2019-05) Washburn, J. Alex; Johnson, Steven M.; Georgiadis, Millie M.; Hoang, Quyen Q.
    Current Mycobacterium tuberculosis (Mtb) treatments suffer from an increase in antibiotic resistance strains and the lack of efficacy against latent state tuberculosis, thus novel approaches targeting different mechanisms of action are needed. One strategy to target Mtb is to target protein homeostasis pathways by inhibiting molecular chaperones, in particular, GroEL/ES (HSP60/10) chaperonin systems. Mtb has two homologs of GroEL, of which GroEL1 is not essential, but is important for cytokine-dependent granuloma formation, and GroEL2 is essential for survival and the likely canonical housekeeping chaperonin. Another strategy to target Mtb is to target the protein tyrosine phosphatase B (PtpB) virulence factor that Mtb secretes into host cells to help evade immune responses. Thus, we envisioned that this analog series might also be capable of inhibiting Mtb PtpB along with GroEL. By developing compound 1 inhibitors that could act on all of GroEL1, GroEL2, and PtpB, we could have an antibiotic candidate that targets all stages of tuberculosis: actively replicating bacteria, bacteria evading host cell immune response, and granuloma formation in latent disease. In the Johnson lab, previous studies explored GroEL/ES inhibitors, with compound 1 being one of the most potent inhibitors, inhibiting both Trypanosoma brucei and Staphylococcus aureus proliferation. In the present study, we have screened previously developed compound 1 analogs, as well as a series of newly synthesized analogs that we term “half-molecules”. In this study, our results indicated two potential avenues to explore for future research. The first is a series of carboxyl-bearing compound 1 inhibitors, compounds 2m-o, 2m-m, and 2m-p, which act solely on Mtb PtpB phosphatase activity without inhibiting GroEL. The second is a series of compound 1 inhibitors (e.g. 20R and 20L) that are able to inhibit both the PtpB phosphatase and GroEL/ES chaperonin system. Thus, this exploratory study showed the possibility of pursuing such a polypharmacological antibiotic strategy against Mtb infections and with further optimization, such dual-targeting GroEL/ES and PtpB inhibitors could be effective against all stages of tuberculosis.
  • Thumbnail Image
    Item
    HSP60/10 chaperonin systems are inhibited by a variety of approved drugs, natural products, and known bioactive molecules
    (Elsevier, 2019-05-01) Stevens, Mckayla; Abdeen, Sanofar; Salim, Nilshad; Ray, Anne-Marie; Washburn, Alex; Chitre, Siddhi; Sivinski, Jared; Park, Yangshin; Hoang, Quyen Q.; Chapman, Eli; Johnson, Steven M.; Biochemistry and Molecular Biology, School of Medicine
    All living organisms contain a unique class of molecular chaperones called 60 kDa heat shock proteins (HSP60 - also known as GroEL in bacteria). While some organisms contain more than one HSP60 or GroEL isoform, at least one isoform has always proven to be essential. Because of this, we have been investigating targeting HSP60 and GroEL chaperonin systems as an antibiotic strategy. Our initial studies focused on applying this antibiotic strategy for treating African sleeping sickness (caused by Trypanosoma brucei parasites) and drug-resistant bacterial infections (in particular Methicillin-resistant Staphylococcus aureus - MRSA). Intriguingly, during our studies we found that three known antibiotics - suramin, closantel, and rafoxanide - were potent inhibitors of bacterial GroEL and human HSP60 chaperonin systems. These findings prompted us to explore what other approved drugs, natural products, and known bioactive molecules might also inhibit HSP60 and GroEL chaperonin systems. Initial high-throughput screening of 3680 approved drugs, natural products, and known bioactives identified 161 hit inhibitors of the Escherichia coli GroEL chaperonin system (4.3% hit rate). From a purchased subset of 60 hits, 29 compounds (48%) re-confirmed as selective GroEL inhibitors in our assays, all of which were nearly equipotent against human HSP60. These findings illuminate the notion that targeting chaperonin systems might be a more common occurrence than we previously appreciated. Future studies are needed to determine if the in vivo modes of action of these approved drugs, natural products, and known bioactive molecules are related to GroEL and HSP60 inhibition.
  • Thumbnail Image
    Item
    Hydroxybiphenylamide GroEL/ES Inhibitors Are Potent Antibacterials against Planktonic and Biofilm Forms of Staphylococcus aureus
    (ACS, 2018-11) Kunkle, Trent; Abdeen, Sanofar; Salim, Nilshad; Ray, Anne-Marie; Stevens, McKayla; Ambrose, Andrew J.; Victorino, José; Park, Yangshin; Hoang, Quyen Q.; Chapman, Eli; Johnson, Steven M.; Biochemistry and Molecular Biology, School of Medicine
    We recently reported the identification of a GroEL/ES inhibitor (1, N-(4-(benzo[d]thiazol-2-ylthio)-3-chlorophenyl)-3,5-dibromo-2-hydroxybenzamide) that exhibited in vitro antibacterial effects against Staphylococcus aureus comparable to vancomycin, an antibiotic of last resort. To follow up, we have synthesized 43 compound 1 analogs to determine the most effective functional groups of the scaffold for inhibiting GroEL/ES and killing bacteria. Our results identified that the benzothiazole and hydroxyl groups are important for inhibiting GroEL/ES-mediated folding functions, with the hydroxyl essential for antibacterial effects. Several analogs exhibited >50-fold selectivity indices between antibacterial efficacy and cytotoxicity to human liver and kidney cells in cell culture. We found that MRSA was not able to easily generate acute resistance to lead inhibitors in a gain-of-resistance assay and that lead inhibitors were able to permeate through established S. aureus biofilms and maintain their bactericidal effects.
  • Thumbnail Image
    Item
    Sulfonamido 2 arylbenzoxazole GroEL/ES inhibitors are potent antibacterials against methicillin resistant Staphylococcus aureus (MRSA)
    (ACS, 2018) Abdeen, Sanofar; Kunkle, Trent; Salim, Nilshad; Ray, Anne-Marie; Mammadova, Najiba; Summers, Corey; Stevens, Mckayla; Ambrose, Andrew J.; Park, Yangshin; Schultz, Peter G.; Horwich, Arthur L.; Hoang, Quyen; Chapman, Eli; Johnson, Steven M.; Biochemistry and Molecular Biology, School of Medicine
    Extending from a study we recently published examining the antitrypanosomal effects of a series of GroEL/ES inhibitors based on a pseudosymmetrical bis-sulfonamido-2-phenylbenzoxazole scaffold, here, we report the antibiotic effects of asymmetric analogs of this scaffold against a panel of bacteria known as the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). While GroEL/ES inhibitors were largely ineffective against K. pneumoniae, A. baumannii, P. aeruginosa, and E. cloacae (Gram-negative bacteria), many analogs were potent inhibitors of E. faecium and S. aureus proliferation (Gram-positive bacteria, EC50 values of the most potent analogs were in the 1–2 μM range). Furthermore, even though some compounds inhibit human HSP60/10 biochemical functions in vitro (IC50 values in the 1–10 μM range), many of these exhibited moderate to low cytotoxicity to human liver and kidney cells (CC50 values > 20 μM).