Biology subjects

Otoupal, P. B.

Publications and source records attributed to Otoupal, P. B..

4 recordsLinked to original sources

bioRxiv2019

Facile Accelerated Specific Therapeutic (FAST) Platform to Counter Multidrug-Resistance Bacteria

Multidrug-resistant (MDR) bacteria pose a grave concern to global health. This problem is further aggravated by a lack of new and effective antibiotics and countermeasure platforms that can sustain the creation of novel antimicrobials in the wake of new outbreaks or evolution of resistance to antibiotics. To address this, we have developed a Facile Accelerated Specific Therapeutic (FAST) platform that can develop effective therapies against MDR bacteria within a week. Our FAST platform combines four essential modules- design, build, test, and delivery-of drug development cycle. The design module comprises a bioinformatics toolbox that predicts sequence-specific peptide nucleic acids (PNAs) that target non-traditional pathways and genes of bacteria in minutes. The build module constitutes in-situ synthesis and validation of selected PNAs in less than four days and efficacy testing within a day. As a proof of concept, these PNAs were tested against MDR clinical isolates. Here we tested Enterobacteriaceae including carbapenem-resistant Escherichia coli, extended-spectrum beta-lactamase (ESBL) Klebsiella pneumoniae, New Delhi Metallo-beta-lactamase-1 carrying Klebsiella pneumoniae and MDR Salmonella enterica. PNAs showed significant growth inhibition for 82% of treatments, with nearly 18% of the treatments leading to more than 97% decrease. Further, these PNAs are capable of potentiating antibiotic activity in the clinical isolates despite presence of cognate resistance genes. Finally, FAST offers a novel delivery approach to overcome limited transport of PNAs into mammalian cells to clear intracellular infections. This method relies on repurposing the bacterial Type III secretion system in conjunction with a kill switch that is effective at eliminating 99.6% of an intracellular Salmonella infection in human epithelial cells. Our findings demonstrate the potential of the FAST platform in treating MDR bacteria in a rapid and effective manner.

bioengineering↗

bioRxiv2019

Potentiating antibiotic treatment using fitness-neutral gene expression perturbations

The rapid proliferation of multidrug-resistant (MDR) bacteria poses a critical threat to human health, for which new antimicrobial strategies are desperately needed. Here we outline a strategy for combating bacterial infections by administering fitness neutral gene expression perturbations as co-therapies to potentiate antibiotic lethality. We systematically explored the fitness of 270 gene knockout-drug combinations in Escherichia coli, identifying 114 synergistic interactions. Genes revealed in this screen were subsequently perturbed at the transcriptome level via multiplexed CRISPR-dCas9 interference to induce antibiotic synergy. These perturbations successfully sensitized E. coli to antibiotic treatment without imposing a separate fitness cost. We next administered these fitness neutral gene perturbations as co-therapies to potentiate antibiotic killing of Salmonella enterica in intracellular infections of HeLa epithelial cells, demonstrating therapeutic applicability. Finally, we utilized these results to design peptide nucleic acid (PNA) co-therapies for targeted gene expression reduction in four MDR, clinically isolated bacteria. Two isolates of Klebsiella pneumoniae and E. coli were each exposed to PNAs targeting homologs of the genes csgD, fnr, recA and acrA in the presence of sub-minimal inhibitory concentrations of trimethoprim. We successfully increased each strains susceptibility to trimethoprim treatment and identified eight cases in which re-sensitization occurred without a direct fitness impact of the PNA on MDR strains. Our results highlight a promising approach for combating MDR bacteria which could extend the utility of our current antibiotic arsenal.

synthetic biology↗

bioRxiv2019

Multiplexed CRISPR-Cas9 based genome editing of Rhodosporidium toruloides

Microbial production of biofuels and bioproducts offers a sustainable and economic alternative to petroleum-based fuels and chemicals. The basidiomycete yeast Rhodosporidium toruloides is a promising platform organism for generating bioproducts due to its ability to consume a broad spectrum of carbon sources (including those derived from lignocellulosic biomass) and to naturally accumulate high levels of lipids and carotenoids, two biosynthetic pathways that can be leveraged to produce a wide range of bioproducts. While R. toruloides has great potential, it has a more limited set of tools for genetic engineering relative to more advanced yeast platform organisms such as Yarrowia lipolytica and Saccharomyces cerevisiae. Significant advancements in the past few years have bolstered R. toruloides engineering capacity. Here we expand this capacity by demonstrating the first use of CRISPR-Cas9 based gene disruption in R. toruloides. Stably integrating a Cas9 expression cassette into the genome brought about successful targeted disruption of the native URA3 gene. While editing efficiencies were initially low (0.002%), optimization of the cassette increased efficiencies 364-fold (to 0.6%). Applying these optimized design conditions enabled disruption of another native gene involved in carotenoid biosynthesis, CAR2, with much greater success; editing efficiencies of CAR2 deletion reached roughly 50%. Finally, we demonstrated efficient multiplexed genome editing by disrupting both CAR2 and URA3 in a single transformation. Together, our results provide a framework for applying CRISPR-Cas9 to R. toruloides that will facilitate rapid and high throughput genome engineering in this industrially relevant organism. IMPORTANCEMicrobial biofuel and bioproduct platforms provide access to clean and renewable carbon sources that are more sustainable and environmentally friendly than petroleum-based carbon sources. Furthermore, they can serve as useful conduits for the synthesis of advanced molecules that are difficult to produce through strictly chemical means. R. toruloides has emerged as a promising potential host for converting renewable lignocellulosic material into valuable fuels and chemicals. However, engineering efforts to improve the yeasts production capabilities have been impeded by a lack of advanced tools for genome engineering. While this is rapidly changing, one key tool remains unexplored in R. toruloides; CRISPR-Cas9. The results outlined here demonstrate for the first time how effective multiplexed CRISPR-Cas9 gene disruption provides a framework for other researchers to utilize this revolutionary genome-editing tool effectively in R. toruloides.

synthetic biology↗

bioRxiv2018

Design of a de novo aggregating antimicrobial peptide and bacterial conjugation delivery system

Traditional antibiotics are reaching obsolescence as a consequence of antibiotic resistance; therefore novel antibiotic approaches are needed. A recent non-traditional approach involves formation of protein aggregates as antimicrobials to disrupt bacterial homeostasis. Previous work on protein aggregates has focused on genome mining for aggregation-prone sequences in bacterial genomes rather than on rational design of aggregating antimicrobial peptides. Here, we use a synthetic biology approach to design an artificial gene encoding the first de novo aggregating antimicrobial peptide. This artificial gene, opaL (overexpressed protein aggregator Lipophilic), disrupts bacterial homeostasis by expressing extremely hydrophobic peptides. When this hydrophobic sequence is disrupted by acidic residues, consequent aggregation and antimicrobial effect decreases. Further, to deliver this artificial gene, we developed a probiotic approach using RK2, a broad host range conjugative plasmid, to transfer opaL from donor to recipient bacteria. We utilize RK2 to mobilize a shuttle plasmid carrying the opaL gene by adding the RK2 origin of transfer. We show that opaL is non-toxic to the donor, allowing for maintenance and transfer since its expression is under control of a promoter with a recipient-specific T7 RNA polymerase. Upon mating of donor and recipient Escherichia coli, we observe selective growth repression in T7 polymerase expressing recipients. This technique could be used to target desired pathogens by selecting pathogen-specific promoters to control opaL expression. This system provides a basis for the design and delivery of novel antimicrobial peptides.\n\nImportanceThe growing threat of antibiotic resistance necessitates new treatment options for bacterial infections that are recalcitrant to traditional antimicrobials. Existing methods usually involve small-molecule compounds which interfere with essential processes in bacterial cells. By contrast, protein aggregates operate by causing widespread disruption of bacterial homeostasis and may provide a new method for combating infections. We used rational design to create and test an aggregating de novo antimicrobial peptide, OpaL. In addition, we employed bacterial conjugation to deliver the opaL gene from donor bacteria to recipient bacteria while using a strain-specific promoter to ensure that OpaL was only expressed in targeted recipients. To the best of our knowledge, this represents the first design for a de novo peptide with aggregation-mediated antimicrobial activity. We envision that OpaLs design parameters could be used in developing a new class of antimicrobial peptides to help treat antibiotic resistant infections.

microbiology↗