Project description:Methanococcus maripaludis is a methanogenic archaeon. Within its genome, there are two operons for membrane associated hydrogenases, eha and ehb. To investigate the regulation of ehb on the cell, an S40 mutant was constructed in such a way that a portion of the ehb operon was replaced by pac cassette in the wild type parental strain S2 (done by Whitman's group at the University of Georgia). The S40 and S2 strains were grown in 14N and 15N media with acetate separately. A biological replicate was made by switching the media. Mass spectrometry based quantitative proteomics were done on the mixtures to investigate the differences in expression patterns between S40 and S2. Keywords: isotope labeling mass spectrometry, quantitative proteomics
Project description:We report the usage of ChIP-mass spectrometry in identifying proteins and histone modifications involved in Drosophila dosage compensation. We identified a chromatin targeting factor, CG4747, that is involved in recognition of H3K36me3 and robust recruitment of the Drosophila MSL complex to its correct targets on the male X chromosome. ChIP-seq with PAP antibody of Drosophila larvae expressing C-terminally TAP-tagged CG4747.
Project description:Thalidomide and its derivatives lenalidomide and pomalidomide (IMiDs) are effective treatments of hematologic malignancies. It was shown that IMiDs impart gain of function properties to the CUL4-RBX1-DDB1-CRBN (CRL4CRBN) ubiquitin ligase that enable binding, ubiquitination and degradation of key therapeutic targets such as IKFZ1, IKZF3 and CSNK1A1. While these substrates have been implicated as efficacy targets in multiple myeloma (MM) and 5q deletion associated myelodysplastic syndrome (del(5q)-MDS), other targets likely exist. Using a pulse-chase SILAC mass spectrometry-based proteomics approach, we demonstrate that lenalidomide induces the ubiquitination and degradation of ZFP91. We establish that ZFP91 is a bona fide IMiD dependent CRL4CRBN substrate and further show that ZFP91 harbors a zinc finger (ZnF) motif, related to the IKZF1/3 ZnF, critical for IMiD dependent CRBN binding. These findings demonstrate that single time point pulse-chase SILAC mass spectrometry-based proteomics (pSILAC-MS) is a sensitive approach for target identification of small molecules inducing selective protein degradation.
Project description:More than half of the mass spectra could not be identified in most proteome mass spectrometry experiments. Various modifications have been considered as a major reason. Open search strategy was then introduced to solve this problem, however, lacking thorough quality assessment using independent information. Here, we used the “Suspicious Discovery Rate (SDR)” based on the translatome sequencing (RNC-seq) as an independent source to assess the proteome open search strategy. We found that the open search strategy increased the spectra utilization with the cost of increasing suspicious identifications that lacks translation evidence. We further suggested that restricting the peptide FDR below 0.1% would efficiently control the suspicious identifications of open search methods and enhanced the confidence of the peptide identification with modifications than the narrow window search. These results facilitated the proper use of open search methods for higher quality of proteome identifications with the information of post-translational modifications and single amino acid polymorphisms
Project description:We report the usage of ChIP-mass spectrometry in identifying proteins and histone modifications involved in Drosophila dosage compensation. We identified a chromatin targeting factor, CG4747, that is involved in recognition of H3K36me3 and robust recruitment of the Drosophila MSL complex to its correct targets on the male X chromosome.
Project description:The locations of transcriptional enhancers and promoters were recently mapped in many mammalian cell types. Proteins that bind those regulatory regions can determine cell identity but have not been systematically identified. Here we purify native enhancers, promoters or heterochromatin from embryonic stem cells by chromatin immunoprecipitations (ChIP) for characteristic histone modifications and identify associated proteins using mass spectrometry (MS). 239 factors are identified and predicted to bind enhancers or promoters with different levels of activity, or heterochromatin. Published genome-wide data indicate a high accuracy of location prediction by ChIP-MS. A quarter of the identified factors are important for pluripotency and includes Oct4, Esrrb, Klf5, Mycn and Dppa2, factors that drive reprogramming to pluripotent stem cells. We determined the genome-wide binding sites of Dppa2 and find that Dppa2 operates outside the classical pluripotency network. Our ChIP-MS method provides a detailed read-out of the transcriptional landscape representative of the investigated cell type.
Project description:We present a combinatorial approach, integrating experimental data from small protein-optimized mass spectrometry (MS) and ribosome profiling (Ribo-seq), to generate a high confidence inventory of small proteins in the model archaeon Haloferax volcanii.