Project description:Multiple immune pathways in humans conjugate ubiquitin-like proteins to virus and host molecules as a means of antiviral defense. Here we studied an anti-phage defense system in bacteria, comprising a ubiquitin-like protein, ubiquitin-conjugating enzymes E1 and E2, and a deubiquitinase. We show that during phage infection, this system specifically conjugates the ubiquitin-like protein to the phage central tail fiber, a protein at the tip of the tail that is essential for tail assembly as well as for recognition of the target host receptor. Following infection, cells encoding this defense system release a mixture of partially assembled, tailless phage particles, and fully assembled phages in which the central tail fiber is obstructed by the covalently attached ubiquitin-like protein. These phages exhibit severely impaired infectivity, explaining how the defense system protects the bacterial population from the spread of phage infection. Our findings demonstrate that conjugation of ubiquitin-like proteins is an antiviral strategy conserved across the tree of life.
Project description:Two immunoprecipitation datasets of phage SECphi27 and SECphi4 modified by the Bil defense system. For both phages, control samples with a mutated Bil defense system were run.
Project description:Multi-modal measurements of single cell profiles are a powerful tool for characterizing cell states and regulatory mechanisms. While current methods allow profiling of RNA along with either readouts of chromatin or protein, connecting chromatin state to protein levels remains a barrier. Here, we developed PHAGE-ATAC, a method that uses engineered camelid single-domain antibody (‘nanobody’)-displaying phages for simultaneous single-cell measurement of surface proteins, chromatin accessibility profiles, and mtDNA-based clonal tracing through a single-cell and massively parallel droplet-based assay of transposase-accessible chromatin with sequencing (ATAC-seq). We demonstrate PHAGE-ATAC for multimodal analysis in primary human immune cells, for multiplexing, for intracellular protein analysis, and for the detection of SARS-CoV-2 spike protein. Finally, we construct a synthetic high-complexity phage library for selection of novel antigen-specific nanobodies that bind cells of particular molecular profiles, opening a new avenue for protein detection, cell characterization and screening with single-cell genomics.
Project description:Multi-modal measurements of single cell profiles are a powerful tool for characterizing cell states and regulatory mechanisms. While current methods allow profiling of RNA along with either readouts of chromatin or protein, connecting chromatin state to protein levels remains a barrier. Here, we developed PHAGE-ATAC, a method that uses engineered camelid single-domain antibody (‘nanobody’)-displaying phages for simultaneous single-cell measurement of surface proteins, chromatin accessibility profiles, and mtDNA-based clonal tracing through a single-cell and massively parallel droplet-based assay of transposase-accessible chromatin with sequencing (ATAC-seq). We demonstrate PHAGE-ATAC for multimodal analysis in primary human immune cells, for multiplexing, for intracellular protein analysis, and for the detection of SARS-CoV-2 spike protein. Finally, we construct a synthetic high-complexity phage library for selection of novel antigen-specific nanobodies that bind cells of particular molecular profiles, opening a new avenue for protein detection, cell characterization and screening with single-cell genomics.
Project description:Multi-modal measurements of single cell profiles are a powerful tool for characterizing cell states and regulatory mechanisms. While current methods allow profiling of RNA along with either readouts of chromatin or protein, connecting chromatin state to protein levels remains a barrier. Here, we developed PHAGE-ATAC, a method that uses engineered camelid single-domain antibody (‘nanobody’)-displaying phages for simultaneous single-cell measurement of surface proteins, chromatin accessibility profiles, and mtDNA-based clonal tracing through a single-cell and massively parallel droplet-based assay of transposase-accessible chromatin with sequencing (ATAC-seq). We demonstrate PHAGE-ATAC for multimodal analysis in primary human immune cells, for multiplexing, for intracellular protein analysis, and for the detection of SARS-CoV-2 spike protein. Finally, we construct a synthetic high-complexity phage library for selection of novel antigen-specific nanobodies that bind cells of particular molecular profiles, opening a new avenue for protein detection, cell characterization and screening with single-cell genomics.
Project description:Genomic material isolated from purified phage YerA41 lysate was shown to contain RNA. YerA41 phage lysate was RNase treated to remove phage-external RNA and total RNA was then isolated from the phage preparate using Qiagen Rneasy mini kit. The isolated RNA was sequenced to elucidate its origin. The results suggested that the RNA originated from intact ribosomes of the host bacterium that contaminated the phage lysate.
Project description:To better understand host/phage interactions and the genetic bases of phage resistance in a model system relevant to potential phage therapy, we isolated several spontaneous mutants of the USA300 S. aureus clinical isolate NRS384 that were resistant to phage K. Six of these had a single missense mutation in the host rpoC gene, which encodes the RNA polymerase beta prime subunit. To examine the hypothesis that the mutations in the host RNA polymerase affect the transcription of phage genes, we performed RNA-seq analysis on total RNA samples collected from NRS384 wild-type (WT) and rpoC G17D mutant cultures infected with phage K, at different time points after infection. Infection of the WT host led to a steady increase of phage transcription relative to the host. Our analysis allowed us to define different early, middle, and late phage genes based on their temporal expression patterns and group them into transcriptional units. Predicted promoter sequences defined by conserved -35, -10, and in some cases extended -10 elements were found upstream of early and middle genes. However, sequences upstream of late genes did not contain clear, complete, canonical promoter sequences, suggesting that factors in addition to host RNA polymerase are required for their regulated expression. Infection of the rpoC G17D mutant host led to a transcriptional pattern that was similar to the WT at early time points. However, beginning at 20 minutes after infection, transcription of late genes (such as phage structural genes and host lysis genes) was severely reduced. Our data indicate that the rpoCG17D mutation prevents the expression of phage late genes, resulting in a failed infection cycle for phage K. In addition to illuminating the global transcriptional landscape of phage K throughout the infection cycle, these studies can inform our investigations into the bases of phage K’s control of its transcriptional program as well as mechanisms of phage resistance.
Project description:hvKP ATCC43816 and its lytic phage H5 were employed as a phage-antibiotic combination model. Based on the comprehensive characterization of phages, including cryo-electron microscopy, we evaluated the synergic effect of H5 on bacterial killing in vitro when combined with multiple antibiotics, and analyzed the advantages of phage-antibiotic combinations from an evolutionary perspective and proposes a novel PAS mechanism by using ceftazidime as an example.
Project description:To development of our gene expression, we have employed whole rhesus monkey genome microarray expression profiling as a discovery platform to identify genes with the potential to induce immune response. The peripheral blood from rhesus macaques, who were immunized in groups of three with the capsular polysaccharide (CPS antigen), carrier protein tetanus toxoid (TT) or conjugate vaccine via intramuscular injection (i.m.) in the anterolateral thigh on days 0, 30 and 60 using the formulations, were obtained on days 0, 30, 60 and 90. PBMCs were collected for microarray assays. Dynamic expression variations of eight genes (KLRC1, LGALS13, LTB4DH, NUAK1, VNN2, GALNT3, LOC710050 and LOC716305) were maintained in Hib conjugate vaccine group throughout experiment comparing with the CPS antigen group and carrier protein TT group.
Project description:Large-genome bacteriophages (jumbo phages) of the Chimalliviriadae family assemble a nucleus-like compartment bounded by a protein shell that protects the replicating phage genome from host-encoded restriction enzymes and CRISPR/Cas nucleases. While the nuclear shell provides broad protection against host nucleases, it necessitates transport of mRNA out of the nucleus-like compartment for translation by host ribosomes, and transport of specific proteins into the nucleus-like compartment to support DNA replication and mRNA transcription. Here we identify a conserved phage nuclear shell-associated protein that we term chimallin C (ChmC), which adopts a nucleic acid-binding fold, binds RNA with high affinity in vitro and binds phage mRNAs in infected cells. ChmC also forms phase-separated condensates with RNA. Targeted knockdown of ChmC using mRNA-targeting Cas13d halts infections at an early stage. Taken together, our data suggest that the conserved ChmC protein acts as a chaperone for phage mRNAs, potentially stabilizing these mRNAs and driving their translocation through the nuclear shell to promote translation and infection progression.