Biology subjects

Bogyo, M.

Publications and source records attributed to Bogyo, M..

33 records · Page 2Linked to original sources

bioRxiv2022

Chemoproteomic identification of a dipeptidyl peptidase 4 (DPP4) homolog in Bacteroides thetaiotaomicron important for envelope integrity and fitness

Serine hydrolases play important roles in signaling and human metabolism, yet little is known about the functions of these enzymes in gut commensal bacteria. Using bioinformatics and chemoproteomics, we identify serine hydrolases in the gut commensal Bacteroides thetaiotaomicron that are specific to the Bacteroidetes phylum. Two are predicted homologs of the human protease dipeptidyl peptidase 4 (hDPP4), a key enzyme that regulates insulin signaling. Functional studies reveal that BT4193 is a true homolog of hDPP4 while the other is misannotated and is a proline-specific triaminopeptidase. We demonstrate that BT4193 is important for envelope integrity and is inhibited by FDA-approved type 2 diabetes drugs that target hDPP4. Loss of BT4193 reduces B. thetaiotaomicron fitness during in vitro growth within a diverse community. Taken together, our findings suggest that serine hydrolases contribute to gut microbiota dynamics and may be off-targets for existing drugs that could cause unintended impact on the microbiota.

microbiology↗

bioRxiv2021

A screen of covalent inhibitors in Mycobacterium tuberculosis identifies serine hydrolases involved in lipid metabolism as potential therapeutic targets

The increasing incidence of antibiotic-resistant Mycobacterium tuberculosis infections is a global health threat necessitating the development of new antibiotics. Serine hydrolases (SHs) are a promising class of targets because of their importance for the synthesis of the mycobacterial cell envelope. We screened a library of small molecules containing serine-reactive electrophiles and identified narrow spectrum inhibitors of M. tuberculous growth. Using these lead molecules, we performed competitive activity-based protein profiling and identified multiple SH targets, including enzymes with uncharacterized functions. Lipidomic analyses of compound-treated cultures revealed an accumulation of free lipids and a substantial decrease in lipooligosaccharides, linking SH inhibition to defects in cell envelope biogenesis. Mutant analysis revealed a path to resistance via the synthesis of mycocerates, but not through mutations to target enzymes. Our results suggest that simultaneous inhibition of multiple SH enzymes is likely to be an effective therapeutic strategy for the treatment of M. tuberculosis infections.

microbiology↗

bioRxiv2020

Toxoplasma gondii serine hydrolases regulate parasite lipid mobilization during growth and replication within the host

The intracellular protozoan parasite Toxoplasma gondii must scavenge cholesterol and other lipids from the host to facilitate intracellular growth and replication. Enzymes responsible for neutral lipid synthesis have been identified but there is no evidence for enzymes that catalyze lipolysis of cholesterol esters and esterified lipids. Here we characterize several T. gondii serine hydrolases with esterase and thioesterase activities that were previously thought to be depalmitoylating enzymes. We find they do not cleave palmitoyl thiol esters but rather hydrolyze short chain lipid esters. Deletion of one of the hydrolases results in alterations in levels of multiple lipids species. We also identify small molecule inhibitors of these hydrolases and show that treatment of parasites results in phenotypic defects reminiscent of parasites exposed to excess cholesterol or oleic acid. Together, these data characterize enzymes necessary for processing lipids critical for infection and highlight the potential for targeting parasite hydrolases for therapeutic applications. HighlightsO_LIBioinformatic and biochemical characterization of T. gondii serine hydrolases reveals substrate preference between enzymes with similar catalytic fold C_LIO_LIT. gondii serine hydrolases previously thought to be depalmitoylases are lipid metabolizing enzymes C_LIO_LIT. gondii lipid metabolism pathways utilize enzymes that are viable therapeutic targets C_LI

microbiology↗

bioRxiv2020

Challenges for targeting SARS-CoV-2 proteases as a therapeutic strategy for COVID-19

Two proteases produced by the SARS-CoV-2 virus, Mpro and PLpro, are essential for viral replication and have become the focus of drug development programs for treatment of COVID-19. We screened a highly focused library of compounds containing covalent warheads designed to target cysteine proteases to identify new lead scaffolds for both Mpro and PLpro proteases. These efforts identified a small number of hits for the Mpro protease and no viable hits for the PLpro protease. Of the Mpro hits identified as inhibitors of the purified recombinant protease, only two compounds inhibited viral infectivity in cellular infection assays. However, we observed a substantial drop in antiviral potency upon expression of TMPRSS2, a transmembrane serine protease that acts in an alternative viral entry pathway to the lysosomal cathepsins. This loss of potency is explained by the fact that our lead Mpro inhibitors are also potent inhibitors of host cell cysteine cathepsins. To determine if this is a general property of Mpro inhibitors, we evaluated several recently reported compounds and found that they are also effective inhibitors of purified human cathepsin L and B and showed similar loss in activity in cells expressing TMPRSS2. Our results highlight the challenges of targeting Mpro and PLpro proteases and demonstrate the need to carefully assess selectivity of SARS-CoV-2 protease inhibitors to prevent clinical advancement of compounds that function through inhibition of a redundant viral entry pathway.

microbiology↗

bioRxiv2020

A chemiluminescent protease probe for rapid, sensitive, and inexpensive detection of live Mycobacterium tuberculosis

Tuberculosis (TB) is a top-ten cause of death worldwide. Successful treatment is often limited by insufficient diagnostic capabilities, especially at the point of care in low-resource settings. The ideal diagnostic must be fast, cheap, and require minimal clinical resources while providing high sensitivity, selectivity, and the ability to differentiate live from dead bacteria. We describe here the development of a Fast, Luminescent, and Affordable Sensor of Hip1 (FLASH) for the diagnosis and monitoring of drug sensitivity of Mycobacterium tuberculosis (Mtb). FLASH is a selective chemiluminescent substrate for the Mtb protease Hip1 that when processed, produces visible light that can be measured with a high signal to noise ratio using inexpensive sensors. FLASH is sensitive to fmol of recombinant Hip1 enzyme in vitro and can detect as few as thousands of Mtb cells in culture or in human sputum samples within minutes. The probe is highly selective for Mtb compared to other non-tuberculous mycobacteria and can distinguish live from dead cells. Importantly, FLASH can be used to measure antibiotic killing of Mtb in culture with greatly accelerated timelines compared to traditional protocols. Overall, FLASH has the potential to enhance both TB diagnostics and drug resistance monitoring in resource-limited settings. One Sentence SummaryA luminescent probe enables sensitive detection of Mycobacterium tuberculosis for diagnostics, treatment monitoring, and drug susceptibility testing.

microbiology↗

bioRxiv2020

Plasmodium berghei K13 Mutations Mediate In Vivo Artemisinin Resistance That is Reversed by Proteasome Inhibition

The recent emergence of Plasmodium falciparum (PF) parasite resistance to the first line antimalarial drug artemisinin is of particular concern. Artemisinin resistance is primarily driven by mutations in the PF K13 protein, which enhance survival of early ring stage parasites treated with the artemisinin active metabolite dihydroartemisinin in vitro and associate with delayed parasite clearance in vivo. However, association of K13 mutations with in vivo artemisinin resistance has been problematic due to the absence of a tractable model. Herein, we have employed CRISPR/Cas9 genome editing to engineer selected orthologous PF K13 mutations into the K13 gene of an artemisinin-sensitive, P. berghei (PB) rodent model of malaria. Introduction of the orthologous PF K13 F446I, M476I, Y493H and R539T mutations into PB K13 produced gene-edited parasites with reduced susceptibility to dihydroartemisinin in the standard 24-hour in vitro assay and increased survival in an adapted in vitro ring-stage survival assay. Mutant PB K13 parasites also displayed delayed clearance in vivo upon treatment with artesunate and achieved faster recrudescence upon treatment with artemisinin. Orthologous C580Y and I543T mutations could not be introduced into PB while the equivalent of the M476I and R539T mutations resulted in significant growth defects. Furthermore, a Plasmodium-selective proteasome inhibitor strongly synergized dihydroartemisinin action in these PB K13 mutant lines, providing further evidence that the proteasome can be targeted to overcome ART resistance. Taken together, our work provides clear experimental evidence for the involvement of K13 polymorphisms in mediating susceptibility to artemisinins in vitro, and most importantly under in vivo conditions. IMPORTANCERecent successes in malaria control have been seriously threatened by the emergence of Plasmodium falciparum parasite resistance to the frontline artemisinin drugs in Southeast Asia. P. falciparum artemisinin resistance is associated with mutations in the parasite K13 protein, which associates with a delay in the time required to clear the parasites upon treatment with the drug. Gene editing technologies have been used to validate the role of several candidate K13 mutations in mediating P. falciparum artemisinin resistance in vitro under laboratory conditions. Nonetheless, the causal role of these mutations under in vivo conditions has been a matter of debate. Here, we have used CRISPR/Cas9 gene editing to introduce K13 mutations associated with artemisinin resistance into the related rodent-infecting parasite, P. berghei. Phenotyping of these P. berghei K13 mutant parasites provides evidence of their role in mediating artemisinin resistance in vivo, which supports in vitro artemisinin resistance observations. However, we were unable to introduce some of the P. falciparum K13 mutations (C580Y, I543T) into the corresponding amino acid residues, while other introduced mutations (M476I, R539T equivalents) carried a pronounced fitness cost. Our study provides evidence of a clear causal role of K13 mutations in modulating susceptibility to artemisinins in vitro and in vivo using the well-characterized P. berghei model. We also show that inhibition of the P. berghei proteasome offsets parasite resistance to artemisinins in these mutant lines.

microbiology↗

bioRxiv2020

Blocking palmitoylation of Toxoplasma gondii myosin light chain 1 disrupts glideosome composition but has little impact on parasite motility

Toxoplasma gondii is a widespread apicomplexan parasite that causes severe disease in immunocompromised individuals and the developing fetus. Like other apicomplexans, T. gondii uses an unusual form of gliding motility to invade cells of its hosts and to disseminate throughout the body during infection. It is well established that a myosin-based motor consisting of a Class XIVa heavy chain (TgMyoA) and two light chains (TgMLC1 and TgELC1/2) plays an important role in parasite motility. The ability of the motor to generate force at the parasite periphery is thought to be reliant upon its anchoring and immobilization within a peripheral membrane-bound compartment, the inner membrane complex (IMC). The motor does not insert into the IMC directly; rather, this interaction is believed to be mediated by the binding of TgMLC1 to the IMC-anchored protein, TgGAP45. The binding of TgMLC1 to TgGAP45 is therefore considered a key element in the force transduction machinery of the parasite. TgMLC1 is palmitoylated, and we show here that palmitoylation occurs on two N-terminal cysteine residues, C8 and C11. Mutations that block TgMLC1 palmitoylation disrupt the association of TgMLC1 with the membrane fraction of the parasite in phase partitioning experiments and completely block the binding of TgMLC1 to TgGAP45. Surprisingly, the loss of TgMLC1 binding to TgGAP45 in these mutant parasites has little effect on their ability to initiate or sustain movement. These results question a key tenet of the current model of apicomplexan motility and suggest that our understanding of gliding motility in this important group of human and animal pathogens is not yet complete. ImportanceGliding motility plays a central role in the life cycle of T. gondii and other apicomplexan parasites. The myosin motor thought to power motility is essential for virulence but distinctly different from the myosins found in humans. Consequently, an understanding of the mechanism(s) underlying parasite motility and the role played by this unusual myosin may reveal points of vulnerability that can be targeted for disease prevention and treatment. We show here that mutations that uncouple the motor from what is thought to be a key structural component of the motility machinery have little impact on parasite motility. This finding runs counter to predictions of the current, widely-held "linear motor" model of motility, highlighting the need for further studies to fully understand how apicomplexan parasites generate the forces necessary to move into, out of and between cells of the hosts they infect.

microbiology↗

bioRxiv2020

Design of optical imaging probes by screening of diverse substrate libraries directly in disease tissue extracts

Fluorescently-quenched probes that are specifically activated in the cancer microenvironment have great potential application for diagnosis, early detection and surgical guidance. These probes are often designed to target specific enzymes associated with disease by direct optimization using single purified targets. However, this can result in painstaking chemistry efforts to produce a probe with suboptimal performance when applied in vivo. We describe here an alternate, unbiased activity-profiling approach in which whole tissue extracts are used to directly identify optimal peptide sequences for probe design. Screening of mouse mammary tumor extracts with a hybrid combinatorial substrate library (HyCoSuL) identified a combination of natural and non-natural amino acid residues that could be used to generate highly efficient tumor-specific fluorescently quenched substrate probes. The most effective probe is significantly brighter than any of our previously reported tumor imaging probes designed for specific proteases and robustly discriminates tumor tissue from adjacent healthy tissue in a mouse model of cancer. Importantly, although the probes were developed by screening mouse mammary tumor tissues, they are able to effectively distinguish human ductal carcinomas from normal breast tissue with similar reactivity profiles to those observed in mouse tissues. This new strategy simplifies and enhances the process of probe optimization by direct screening in a tissue of interest without any a priori knowledge of enzyme targets. It has the potential to be applied to advance the development of probes for diverse disease states for which clinical or animal model tissues are available.

bioengineering↗

bioRxiv2020

Structural basis for active-site probes targeting Staphylococcus aureus serine hydrolase virulence factors

Staphylococcus aureus is a major cause of infection in the community and in hospitals. Serine hydrolases play key roles in bacterial homeostasis, in particular biofilms. Activity-based profiling has previously identified a family of serine hydrolases, designated fluorophosphonate-binding hydrolases (Fphs), which contribute to virulence of S. aureus in the biofilm niche. Here we report structures of the putative tributyrin esterase FphF, alone and covalently bound by a substrate analog, and small molecule inhibitors that occupy the hydrophobic substrate-binding pocket. We show that FphF has promiscuous esterase activity. Building from this, we extended our analysis to the wider Fph protein family using homology modeling and docking tools. We predict that other Fph enzymes, including FphB which was linked directly to virulence, may be more specific than FphF. This study provides insight into Fph function and a template for designing new imaging agents, diagnostic probes, and inhibitors to treat S. aureus infections.

biochemistry↗

bioRxiv2019

The antimalarial natural product salinipostin A identifies essential α/β serine hydrolases involved in lipid metabolism in P. falciparum parasites

Salinipostin A (Sal A) is a potent antimalarial marine natural product with an undefined mechanism of action. Using a Sal A-derived activity-based probe, we identify its targets in the Plasmodium falciparum parasite. All of the identified proteins contain /{beta} serine hydrolase domains, and several are essential for parasite growth. One of the essential targets displays high homology to human monoacylglycerol lipase (MAGL) and is able to process lipid esters including a MAGL acylglyceride substrate. This Sal A target is inhibited by the anti-obesity drug Orlistat, which disrupts lipid metabolism and produces disorganized and stalled schizonts similar to Sal A. Resistance selections yielded parasites that showed only minor reductions in sensitivity and that acquired mutations in a protein linked to drug resistance in Toxoplasma gondii. This inability to evolve efficient resistance mechanisms combined with the non-essentiality of human homologs makes the serine hydrolases identified here promising antimalarial targets.

cell biology↗

bioRxiv2019

The clinical drug candidate ebselen attenuates inflammation and promotes microbiome recovery after antibiotic treatment for Clostridium difficile infection

Clostridium difficile infection (CDI) is an enteric bacterial disease that is increasing in prevalence worldwide. C. difficile capitalizes on gut inflammation and microbiome dysbiosis to establish infection, with symptoms ranging from watery diarrhea to toxic megacolon. We recently reported that the safe in human clinical drug candidate ebselen (NCT03013400, NCT01452607, NCT00762671, NCT02603081) has biochemical, cell-based and in vivo efficacy against the bacterial toxins of C. difficile. Here, we show that ebselen treatment reduces recurrence rates and decreases colitis in a hamster relapse model of CDI. Furthermore, ebselen treatment does not alter microbiome diversity but promotes its recovery back to that of healthy controls after antibiotic-induced dysbiosis in both healthy and C. difficile-infected mice. This increased microbiome recovery upon ebselen treatment correlates with a decrease in host-derived inflammatory markers suggesting that the anti-inflammatory properties of ebselen, combined with its anti-toxin function, help to mitigate the major clinical challenges of CDI, including recurrence, microbial dysbiosis, and colitis.

microbiology↗

bioRxiv2019

A phage display approach to identify highly selective covalent binders

Molecules that bind macromolecular targets through direct covalent modification have found widespread applications as activity-based probes (ABPs) and as irreversible drugs. Covalent binders can be used to dynamically monitor the activity of enzymes in complex cellular environments, identify targets and induce permanent binding/inhibition of therapeutically important biomolecules. However, the general reactivity of the electrophiles needed for covalent bond formation makes control of selectivity difficult. There is currently no rapid, robust and unbiased screening method to identify new classes of covalent binding ligands from highly diverse pools of candidate molecules. Here we describe the development of a phage display method to screen for highly selective covalent binding ligands. This approach makes use of a reactive linker to form cyclic peptides on the phage surface while simultaneously introducing an electrophilic warhead to covalently react with a nucleophile on the target. Using this approach, we identified cyclic peptides that selectively and irreversibly inhibited a cysteine protease with nanomolar potency, exceptional specificity and increased serum stability compared to a linear peptide containing the same electrophile. This approach should enable rapid, unbiased screening to identify new classes of highly selective covalent binding ligands for diverse molecular targets.

bioengineering↗

bioRxiv2019

Multivariate ‘AND-gate’ substrate probes as enhanced contrast agents for fluorescence-guided surgery

The greatest challenges for surgical management of cancer are precisely locating lesions and clearly defining the margins between tumors and normal tissues. This is confounded by the characteristics of the tissue where the tumor is located as well as its propensity to form irregular boundaries with healthy tissues. To address these issues, molecularly targeted optical contrast agents have been developed to define margins in real-time during surgery1,2. However, selectivity of a contrast agent is often limited by expression of a target enzyme or receptor in both tumor and healthy tissues. Here we introduce a concept of multivariate AND-gate optical imaging probes that require sequential processing by multiple tumor-specific enzymes to produce a fluorescent signal. This results in dramatically improved specificity as well as overall enhanced sensitivity. This general approach has the potential to be broadly applied to selectively target complex patterns of enzyme activities in diverse disease tissues for detection, treatment and therapy response monitoring.

bioengineering↗

bioRxiv2019

Leveraging peptide substrate libraries to design inhibitors of bacterial Lon protease

Lon is a widely-conserved housekeeping protease found in all domains of life. Bacterial Lon is involved in the recovery from various types of stress, including tolerance to fluoroquinolone antibiotics, and is linked to pathogenesis in a number of organisms. However, detailed functional studies of Lon have been limited by the lack of selective, cell-permeable inhibitors. Here we describe the use of positional scanning libraries of hybrid peptide substrates to profile the primary sequence specificity of bacterial Lon. In addition to identifying optimal natural amino acid binding preferences, we identified several non-natural residues that were leveraged to develop optimal peptide substrates as well as a potent peptidic boronic acid inhibitor of Lon. Treatment of E. coli with this inhibitor promotes UV-induced filamentation and reduces tolerance to ciprofloxacin, phenocopying established lon-deletion phenotypes. It is also non-toxic to mammalian cells due to its increased selectivity for Lon over the proteasome. Our results provide new insight into the primary substrate specificity of Lon and identify substrates and an inhibitor that will serve as useful tools for dissecting the diverse cellular functions of Lon.

microbiology↗

bioRxiv2018

Characterization of P. falciparum dipeptidyl aminopeptidase 3 specificity identifies different amino acid preferences between peptide-based substrates and inhibitors.

Malarial dipeptidyl aminopeptidases (DPAPs) are cysteine proteases important for parasite development thus making them attractive drug targets. In order to develop inhibitors specific to the parasite enzymes it is necessary to map the determinants of substrate specificity of the parasite enzymes and its mammalian homologue cathepsin C (CatC). Here, we screened peptide-based libraries of substrates and covalent inhibitors to characterize the differences in specificity between parasite DPAPs and CatC, and used this information to develop highly selective DPAP1 and DPAP3 inhibitors. Interestingly, while the primary amino acid specificity of a protease is often used to develop potent inhibitors, we show that equally potent and highly specific inhibitors can be developed based on the sequences of non-optimal peptide substrates. Importantly, analysis of previously published data about the specificity of other proteases also unveiled significant discrepancies in the amino acid preference between substrates and inhibitors. In this article, we also discuss important structural and theoretical reasons that might account for these discrepancies. Overall, this study illustrates that focusing the development of protease inhibitors solely on substrate specificity might overlook important structural features that can be exploited to develop highly potent and selective compounds.

biochemistry↗