Project description:Genomic microarrays were used to examine the complex temporal program of gene expression exhibited by bacteriophage T4 during the course of development.The microarray data confirm the existence of distinct early, middle, and late transcriptional classes during the bacteriophage replicative cycle.This approach allows assignment of previously uncharacterized genes to specific temporal classes.The genomic expression data verify many promoter assignments and predict the existence of previously unidentified promoters. Keywords: time course
Project description:Purpose: To investigated the role of MotB in T4 infections Method: NapIV NS were grown to a cell density of ~4 x 10^8 cells/mL (OD600 ~0.4) then infected with either wild-type T4D+ or T4motBam at a MOI of 10. RNA was isolated at 5 post-infection using method II of (Hinton 1989). rRNA subtraction was performed with the bacterial RiboMinus Kit (Ambion) according to manufacturer instructions. cDNA was prepared using the NEBNext strand specific kit (New England BioLabs) according to manufacturer instruction for libraries with 300-450 bp insert size with the following modifications. Illumina adaptors sequences based on TruSeq HT Sample Prep Kits were purchase from Integrated DNA Technologies and used in the ligation step. TruSeq-1 and TruSeq-2 primer were used for PCR enrichment of adaptor ligated DNA. Library size was verified with a Bioanalyzer using an Agilent High Sensitivity DNA kit. The concentration of each library was determined using the KAPA Library Quantification Kit for Illumina platforms. Sequencing was performed by the NIDDK Genomics Core facility using a MiSeq system with the MiSeq 2 x 250 bp Sequencing Kit (Illumina). Result: RNA-seq data revealed that the expression of only six late genes, which decreased from 2 to 4.8-fold, were significantly affected in the T4motBam infection relative to T4 wt at 5 min after infection. The expression of early and middle genes did not change. Conclusion: MotB is a bactericidal DNA-binding protein that improves the fitness of T4 infections.
Project description:Bacteriophages likely constitute the largest biomass on Earth. However, very few phage genomes have been well-characterized, the tailed phage T4 genome being one of them. Even in T4, much of the genome remained uncharacterized. The classical genetic strategies are tedious, compounded by genome modifications such as cytosine hydroxylmethylation and glucosylation which makes T4 DNA resistant to most restriction endonucleases. Here, using the type-II CRISPR-Cas9 system, we report the editing of both modified (ghm-Cytosine) and unmodified (Cytosine) T4 genomes. The modified genome, however, is less susceptible to Cas9 nuclease attack when compared to the unmodified genome. The efficiency of restriction of modified phage infection varied greatly in a spacer-dependent manner, which explains some of the previous contradictory results. We developed a genome editing strategy by codelivering into E. coli a CRISPR-Cas9 plasmid and a donor plasmid containing the desired mutation(s). Single and multiple point mutations, insertions and deletions were introduced into both modified and unmodified genomes. As short as 50-bp homologous flanking arms were sufficient to generate recombinants that can be selected under the pressure of CRISPR-Cas9 nuclease. A 294-bp deletion in RNA ligase gene rnlB produced viable plaques, demonstrating the usefulness of this editing strategy to determine the essentiality of a given gene. These results provide the first demonstration of phage T4 genome editing that might be extended to other phage genomes in nature to create useful recombinants for phage therapy applications.
Project description:UNLABELLED:The genomic DNAs of tailed bacteriophages are commonly modified by the attachment of chemical groups. Some forms of DNA modification are known to protect phage DNA from cleavage by restriction enzymes, but others are of unknown function. Recently, the CRISPR-Cas nuclease complexes were shown to mediate bacterial adaptive immunity by RNA-guided target recognition, raising the question of whether phage DNA modifications may also block attack by CRISPR-Cas9. We investigated phage T4 as a model system, where cytosine is replaced with glucosyl-hydroxymethylcytosine (glc-HMC). We first quantified the extent and distribution of covalent modifications in T4 DNA by single-molecule DNA sequencing and enzymatic probing. We then designed CRISPR spacer sequences targeting T4 and found that wild-type T4 containing glc-HMC was insensitive to attack by CRISPR-Cas9 but mutants with unmodified cytosine were sensitive. Phage with HMC showed only intermediate sensitivity. While this work was in progress, another group reported examples of heavily engineered CRISRP-Cas9 complexes that could, in fact, overcome the effects of T4 DNA modification, indicating that modifications can inhibit but do not always fully block attack. IMPORTANCE:Bacteria were recently found to have a form of adaptive immunity, the CRISPR-Cas systems, which use nucleic acid pairing to recognize and cleave genomic DNA of invaders such as bacteriophage. Historic work with tailed phages has shown that phage DNA is often modified by covalent attachment of large chemical groups. Here we demonstrate that DNA modification in phage T4 inhibits attack by the CRISPR-Cas9 system. This finding provides insight into mechanisms of host-virus competition and also a new set of tools that may be useful in modulating the activity of CRISPR-Cas9 in genome engineering applications.
Project description:Ribosomal stress was evaluated in melanoma cell line CHL-1 after CRISPR editing genomic locus containing SNORD50A/B We have used CRISPR genome editing tool to KD snoRNAs SNORD50A/B from CHL-1 genome and assessed ribosomal binding genome-wide using ribosome profiling
Project description:Purpose: We investigated the effect of the T4 MotB protein on E. coli gene expression Method: E. coli BL21 (DE3) containing either pNW129 or pNW129-MotB were grown to early log phase (OD600 ~ 0.3) then induced with 0.2% arabinose for 20 minutes. T4 phage added to the culture at MOI10. Cells were then harvested at 0, 5, and 10 min time points and total RNA was isolated. The cDNA library was prepared using a modified RNATagSeq workflow as previously described (Shishkin, A.A. et al. 2015 Nat Methods). Optimum fragmentation of the total RNA samples in this library was determined to be 3 min at 94C in FastAP buffer (Thermo Fischer Scientific). The cDNA Library was run on a Bioanalyzer using the Agilent High Sensitivity DNA Kit to evaluate the quality of the library. The concentration of the cDNA library was determined by qPCR using the KAPA Library Quantification Kit (Kapa Biosystems, Wilmington, MA, USA) and CFX96 Real-Time PCR Detection System (Bio-Rad, Hercules, CA, USA). Sequencing was performed by the NIDDK Genomics Core facility using a MiSeq system with the single-end 50 bp Sequencing Kit (Illumina, San Diego, CA, USA). RNA-seq data was processed as previously described using E. coli str. K-12 substr. MG1655 (NC_000913.3) as the reference genome. Differential expression between conditions was represented as a fold change, and genes with both a fold change ≥2 or ≤ 0.5 and adjusted p value ≤ 0.05 were considered significant. Results: RNA-seq data revealed that the expression of 542 E. coli genes were significantly changed after motB expression. The expression of 704 and 706 E. coli genes were changed T4 5 min and 10 min post infection after MotB expression, respectively. After 5 min T4 infection, 34 T4 genes were significantly changed. Conclusion: T4 MotB modifies the pool of host tRNAs, creating a better infection for T4