Project description:We performed a DNA pull-down assay to identify DNA-binding proteins interacting with the cas6 promoter in the M. tuberculosis Δorn strain
Project description:We performed a DNA pull-down assay to identify DNA-binding proteins interacting with the cas6 promoter in the M. tuberculosis Δorn strain
Project description:We have designed a zebrafish genomic microarray to identify DNA-protein interactions in the proximal promoter regions of over 11,000 zebrafish genes. Using these microarrays, together with chromatin immunoprecipitation with an antibody directed against tri-methylated lysine 4 of Histone H3, we demonstrate the feasibility of this method in zebrafish. This approach will allow investigators to determine the genomic binding locations of DNA interacting proteins during development and expedite the assembly of the genetic networks that regulate embryogenesis. Keywords: ChIP-chip
Project description:The metabolome profiles of S. cerevisiae mutants where the promoter of genes predicted to code for peroxisomally localized proteins are swapped with the TEF2 promoter were measured by flow-injection analysis.
Project description:Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, the leading cause of death among all infectious diseases. There are 11 eukaryotic-like serine/threonine protein kinases (STPKs) in Mtb, which are thought to play pivotal roles in cell growth, signal transduction and pathogenesis. However, their underlying mechanisms of action remain largely uncharacterized. In this study, using a Mtb proteome microarray, we have globally identified the binding proteins in Mtb for all of the STPKs, and constructed the first STPK protein interaction (KPI) map that includes 492 binding proteins and 1,027 interactions. Bioinformatics analysis showed that the interacting proteins reflect diverse functions, including roles in two-component system, transcription, protein degradation, and cell wall integrity. Functional investigations confirmed that PknG regulates cell wall integrity through key components of peptidoglycan (PG) biosynthesis, e.g., MurC. The global STPK-KPIs network constructed here is expected to serve as a rich resource for understanding the key signaling pathways in Mtb, thus facilitating drug development and effective control of Mtb.
Project description:G-quadruplexes (G4s) are noncanonical DNA secondary structures formed through the self-association of guanines, and they are distributed widely across the genome. G4 participates in multiple biological processes including gene transcription, and G4-targeted ligands serve as potential therapeutic agents for DNA-targeted therapies. However, genome-wide studies of the exact roles of G4s in transcriptional regulation are still lacking. We found that drug-induced promoter-proximal RNA polymerase II pausing promotes nearby G4 formation, and oppositely, G4 stabilization by G4-targeted ligands globally reduces RNA polymerase II occupancy at gene promoters as well as nascent RNA synthesis. To study the underlying mechanisms by which native G4 affects transcriptional regulation, we annealed the biotin-labeled core promoter DNA to form G4s and performed pull-down assays with nuclear extraction proteins in the presence or absence of TMPyP4. Mass spectrometry analysis was performed to identify the interacting proteins with G4-forming core promoter DNA.
Project description:Tuberculosis caused by Mycobacterium tuberculosis (Mtb) infection remains a huge global public health problem. One striking characteristic of Mtb is its ability to adapt to hypoxia, and thus ensuing transition to dormant state for persistent infection, but how the hypoxia responses of Mtb is regulated remains largely unknown. Here, we performed a quantitative acetylome analysis to compare the acetylation profile of Mtb under aeration and hypoxia, and showed that 377 acetylation sites in 269 proteins of Mtb were significantly change under hypoxia. Especially, deacetylation of Dormancy Survival Regulator (DosR) at K182 promoted the hypoxia response of Mtb and enhanced transcription of DosR-targeted genes. Mechanistically, recombinant DosRK182R protein demonstrated enhanced DNA-binding activity in comparison with DosRK182Q protein. Moreover, Rv0998 was identified as an acetyltransferase that mediates the acetylation of DosR at K182. Deletion of Rv0998 also promoted the adaption of Mtb to hypoxia and transcription of DosR-targeted genes. Mice infected with Mtb strain containing acetylation-defective DosRK182R or lacking Rv0998 had much lower bacterial counts, and less severe histopathological impairments compared with those infected with the wild-type strain. Our findings suggest that hypoxia induces the deacetylation of DosR, which in turn increases its DNA binding ability to promote the transcription of target genes, allowing Mtbto transit to dormancy under hypoxia.
Project description:We performed CovR ChIP-seq analysis in the emm1 strain MGAS2221 and its CovS kinase deficient derivative strain 2221-CovS-E281A. We identified that CovR bound in the promoter regions of nearly all virulence factor encoding genes in the CovR regulon. Additionally, direct CovR binding was observed for numerous genes encoding proteins involved in amino acid metabolism, but we found limited direct CovR binding to genes encoding other transcriptional regulators. The consensus sequence AATRANAAAARVABTAAA was present in the promoters of genes directly regulated by CovR, and mutations of highly conserved positions within this motif relieved CovR repression of the hasA and M2221_0187 promoters. Analysis of strain 2221-CovS-E281A revealed that binding of CovR at repressed, but not activated, promoters is highly dependent on CovR~P state. CovR repressed virulence factor encoding genes could be grouped dependent on how variation in CovR~P differentially impacted DNA binding and gene transcript levels.
Project description:We have designed a zebrafish genomic microarray to identify DNA-protein interactions in the proximal promoter regions of over 11,000 zebrafish genes. Using these microarrays, together with chromatin immunoprecipitation with an antibody directed against tri-methylated lysine 4 of Histone H3, we demonstrate the feasibility of this method in zebrafish. This approach will allow investigators to determine the genomic binding locations of DNA interacting proteins during development and expedite the assembly of the genetic networks that regulate embryogenesis. Genomic array design Microarrays were designed as described below and manufactured by Agilent Technologies (www.agilent.com). Further information on design can be found at http://jura.wi.mit.edu/bioc/gbell/zfish_chip/. Selection of transcription start sites and identification of promoter sequences We interrogated 5 databases: Ensembl, VEGA, Refseq, ZGC full length clones and a database provided by Dr. Leonard Zon (Harvard Medical School, Boston, USA) in order to assemble an extensive list of zebrafish transcripts. The Zon lab database is a hand-curated database of zebrafish genes that have homologues in other species. We included all transcripts that appeared in the manually annotated databases (VEGA, Zon) and in the ZGC full length database. We also identified genes present in any 2 of the 5 databases and included those not already selected. The transcripts were mapped to the zebrafish genome (Zv4, June 2004) obtained from UCSC Bioinformatics (http://genome.ucsc.edu) and the transcription start site (TSS) for each transcript was determined. Transcripts with TSSs within 500bp were clustered into a transcriptional unit (TU) and promoter regions were identified relative to the most upstream TSS. This resulted in the identification of 13,413 TUs and corresponding promoter regions. Each promoter region was extracted and masked for repetitive sequence by RepeatMasker. If the promoter region contained a gap the upstream sequence was also masked. Information on the transcriptional units that were included in the final design can be found at http://jura.wi.mit.edu/bioc/gbell/zfish_chip/. Selection of oligonucleotides 60-mer oligonucleotide probes representing the region between 1.5kb upstream and 0.5kb downstream of the annotated TSS of each transcriptional unit were then designed. Although transcription factors and other DNA binding proteins are known to regulate genes from distances of greater than -1.5kb or + 0.5kb, much information can be gained from regions close to the TSS [45], and the H3K4Me3 mark studied in this paper is found at the most 5â end of a gene, close to the TSS. Selection of 60-mers for the microarrays was essentially as described in [14] using the Zv4 build of the zebrafish genome and a locally customized version of ArrayOligoSelector. 60-mers were chosen so that promoter regions contained approximately one probe every 250bp with a maximum distance between probes for each promoter region set at 600bp. In cases where only one probe could be designed for a particular TU these were not included in the final design. This process yielded 80,839 probes for 11,171 promoter regions We also incorporated several sets of control probes, both positive and negative. On each array there are 1090 probes designed against âgene desertâ regions, which are genomic regions that are unlikely to be bound by transcriptional regulators, and 270 probes designed against Arabidopsis thaliana genes, which are not present in the zebrafish genome (by BLAST). In addition, because our main motivation for making these microarrays is to identify mesodermally-regulated genes we included 7 genes expressed in mesoderm during gastrulation as positive controls (wnt11, flh, vent, msgn1, myod, fgf8, pcdh8). Probes designed against these promoters, which flank from 3-4kb around each TSS, are arrayed 2-4 times on each slide. Since these genes are expressed at gastrula stages to varying degrees, they also serve as a positive controls in this study. Finally there are 2256 controls added by Agilent and a variable number of blank spots. These probes were divided between two microarray slides each with 44,290 features. We refer to these two microarray slides as the âproximal promoter setâ. A proximal promoter set based on these designs as well as an expanded set of 9 slides which contain regions from â9kb to + 3kb relative to the TSS, are available by contacting Agilent (www.agilent.com) or by downloading the design files from http://jura.wi.mit.edu/bioc/gbell/zfish_chip/ for self-manufacture.