Project description:Identification of post translational modifications on Vibrio cholerae protein VesB (from purified VesB and culture supernatant) using in-gel digestion with trypsin, LC-MS/MS, database searching.
Project description:The synthesis of poly(ADP-ribose) (PAR) reconfigures the local environment and recruits repair complexes to damaged chromatin. The degradation of PAR by PARG is essential for progression and completion of DNA repair. Here, we show that inhibition of PARG disrupts homology-directed repair (HDR) mechanisms that underpin alternative telomere lengthening (ALT). By proteomics, we uncovered a novel role for PARylation in regulating the chromatin assembly factor, HIRA in ALT cancer cells. We show that HIRA is enriched at telomeres during G2 phase and is indispensable for histone H3.3 deposition and telomere DNA synthesis. Depletion of HIRA elicits systemic death of ALT cancer cells was mitigated by re-expression of ATRX protein that is frequently inactivated in ALT tumors. We propose that PARylation enables HIRA to fulfill its essential role in the adaptive response due to ATRX deficiency that pervades ALT cancers.
Project description:Alternative lengthening of telomeres (ALT) is a homology-directed repair (HDR) mechanism of telomere elongation that controls proliferation in subsets of highly aggressive cancer. Recent studies have revealed that TERRA (telomere repeat-containing RNA) acts to initiate ALT-associated HDR (ALT-HDR). Here we report that RAD51AP1, a crucial ALT factor, interacts with TERRA and utilizes it to generate D- and R- loop HR intermediates. We also show that RAD51AP1 binds to and may generate and potentially stabilize TERRA-containing R-loops as RAD51AP1 depletion reduces R-loop formation at telomere DNA breaks. Proteomic analyses uncover a new role for RAD51AP1 mediated TERRA R-loop homeostasis in a mechanism of chromatin-directed suppression of TERRA and prevention of transcription-replication collisions during ALT-HDR. Intriguingly, we find that both TERRA binding and this non-canonical function of RAD51AP1 require its intrinsic SUMO-SIM regulatory axis. These findings provide new insights into the multi-contextual functions of RAD51AP1 within the ALT mechanism and regulation of TERRA.
Project description:This study is an analysis of changes in gene expression during stringent response in Vibrio cholerae. V. cholerae cells in mid-log were treated with serine hydroxamate and gene expression was compared to untreated cells. Keywords: Stress response, stringent response
Project description:The transcriptional events driving specification of the kidney have been well characterized. However, it remains undetermined how initial kidney field size is established, patterned, and proportioned. Lhx1 is a transcription factor expressed in the kidney anlage and is required for specification of the kidney field, but few Lhx1 interacting cofactors or downstream targets have been identified. By tandem-affinity purification, we isolated Furry (FRY), a multifunctional protein that acts as a transcriptional co-repressor of microRNAs. We found that Xenopus embryos depleted of fry exhibit loss of the kidney field, phenocopying the lhx1 depleted animals. In addition, we demonstrated synergism between Fry and Lhx1, identified candidate microRNAs regulated by the pair, and confirmed these microRNA clusters influence specification of the kidney field. Therefore, our data shows that a tissue-specific transcription factor, Lhx1, interacts with a broadly expressed microRNA repressor, Fry, to establish the kidney field.
Project description:Temperature is a crucial environmental signal that govers the occurrence of Vibrio cholerae and cholera outbreaks. To understand how temperature impacts the transcriptome of V. cholerae we performed whole-genome level transcriptional profiling using custom microarrays on cells grown at human body temperature (37 C) then shifted to temperatures V. cholerae experience in the environment (15 C and 25 C).
Project description:Question Addressed: What is the level of expression of genes in Vibrio cholerae recovered from various conditions. These conditions include samples recovered directly from patients (O139 from stool samples from ICDDR,B and N16961 from stool samples from a vaccine trial held in Cincinnati) as well as standard logarithmic and stationary phase grown bacteria. Labeling reactions were performed in duplicate for each stool derived and in quadruplicate for each in vitro grown strain. A common reference was used for each slide, it was composed of RNA from the exponentially growing 92A1552 V. cholerae strain
Project description:Environmental isolates of Vibrio cholerae from California coastal water compared to reference strain N16961. A genotyping experiment design type classifies an individual or group of individuals on the basis of alleles, haplotypes, SNP's. Keywords: genotyping_design; array CGH