Project description:Recombinant antibodies to histone post-translational modifications (PTMs), with their essentially infinite renewability, could fundamentally eliminate a major source of low reproducibility in epigenetics research. Here, we report new recombinant antibodies to trimethylated Lys4 and Lys9, respectively, on histone H3. Quantitative characterization demonstrated their exquisite specificity and high affinity, and they performed well in common epigenetics applications, including ChIP. These results demonstrate the feasibility of generating recombinant antibodies to a range of histone marks, which will accelerate epigenetics research. We characterized recombinant antibodies with native ChIP using HEK293 cells followed by deep sequencing.
Project description:To understand the impact of alternative translation initiation on a proteome, we performed the first study on protein turnover using positional proteomics and ribosome profiling to distinguish between N-terminal proteoforms of individual genes. Overall, we monitored the stability of 1,941 human N-terminal proteoforms, including 147 N-terminal proteoform pairs that originate from alternative translation initiation, alternative splicing or incomplete processing of the initiator methionine. Ribosome profiling of lactimidomycin and cycloheximide treated human Jurkat T-lymphocytes
Project description:The aim of the study was to determine the epitope targeted by a panel of Human Fabs. Fabs were diluted at 1:50 and incubated on a non-commercial Protein Microarray platform printed with fHbp, NHBA and NadA specific recombinant protein fragments and full length fHbp, NHBA and NadA of different variants. Overall design: A panel of recombinant fragments of different length spanning the entire sequence of fHbp, NHBA and NadA plus different full length fHbp, NHBA and NadA variants were printed in 8 or 16 replicated on non-commercial Protein Microarray. All fragments were expressed in E. coli as either glutathione S-transferase-, His-tagged or TRX-fusions, purified from the cytoplasmic fraction as soluble forms. Human IgG (at 8 different concentration points) was distributed in each array copy as control. Fabs were profiled for anti-Human IgG specific analysis of reactivity to the spotted proteins.
Project description:In this study on human Tousled-Like-Kinase 2 (TLK2) mass spectrometry-based analysis was applied as part of a molecular characterization of TLK2 in the aim to increase the understanding of the mode of activation of this protein. Specifically, different TLK2 constructs were expressed analyzed to generate a “phosphorylation map” of the TLK2 protein. To analyse the phosphorylation state of TLK2 we used recombinant protein purified from HEK293. Samples of different TLK2 constructs were used for in-gel digestion and analysed by mass spectrometry. All samples were prepared and run in triplicates for label-free quantification. Explanation for MS raw files with TLK2 construct included: KD: Kinase-dead TLK2 construct with mutation D613A, N-terminal His- and Strep-tag. wt: Active form of TLK2, canonical sequence, N-terminal His- and Strep-tag. full: Full-length canonical sequence (1-772), N-terminal His- and Strep-tag. trunc: Truncated TLK2 sequence (191-772), N-terminal His- and Strep-tag.
Project description:Capillary zone electrophoresis (CZE)-tandem mass spectrometry (MS/MS) has been recognized as an efficient approach for top-down proteomics recently for its high-capacity separation and highly sensitive detection of proteoforms. However, the commonly used collision-based dissociation methods often cannot provide extensive fragmentation of proteoforms for thorough characterization. Activated ion electron transfer dissociation (AI-ETD), that combines infrared photoactivation concurrent with ETD, has shown better performance for proteoform fragmentation than higher energy-collisional dissociation (HCD) and standard ETD. Here, we present the first application of CZE-AI-ETD on an Orbitrap Fusion Lumos mass spectrometer for large-scale top-down proteomics of Escherichia coli (E. coli) cells. CZE-AI-ETD outperformed CZE-ETD regarding proteoform and protein identifications (IDs). CZE-AI-ETD reached comparable proteoform and protein IDs with CZE-HCD. CZE-AI-ETD tended to generate better expectation values (E-values) of proteoforms than CZE-HCD and CZE-ETD, indicating higher quality of MS/MS spectra from AI-ETD respecting the number of sequence-informative fragment ions generated. CZE-AI-ETD showed great reproducibility regarding the proteoform and protein IDs with relative standard deviations less than 4% and 2% (n=3). Coupling size exclusion chromatography (SEC) to CZE-AI-ETD identified 3028 proteoforms and 387 proteins from E. coli cells with 1% spectrum-level and 5% proteoform-level false discovery rates. The data represents the largest top-down proteomics dataset using the AI-ETD method so far. Single-shot CZE-AI-ETD of one SEC fraction identified 957 proteoforms and 253 proteins. N-terminal truncations, signal peptide cleavage, N-terminal methionine removal and various post-translational modifications including protein N-terminal acetylation, methylation, S-thiolation, disulfide bonds, and lysine succinylation were detected.
Project description:Primary lymphoma of the central nervous system (PCNSL) is a diffuse large B cell lymphoma confined to the CNS. In order to elucidate its peculiar organ tropism, we generated recombinant antibodies (recAb) identical with the BCR of a series of 23 PCNSL from immunocompetent patients. While none of the recAb showed self-reactivity upon testing with common autoantigens, they recognized 1547 proteins present on a large-scale protein microarray. Interestingly, proteins recognized by the recAb are physiologically expressed by CNS neurons (GRINL1A, centaurin-α, BAIAP2). Furthermore, 87% (20/23) of the recAb including all antibodies derived from IGHV4 34 using PCNSL recognized galectin-3, which was upregulated on microglia/macrophages, astrocytes, and cerebral endothelial cells upon CNS invasion by PCNSL. Thus, PCNSL Ig may recognize CNS proteins as self-antigens. Their interaction may contribute to BCR signaling with sustained NF-κB activation and, ultimately, may foster tumor cell proliferation and survival. These data may also explain, at least in part, the affinity of the tumor cells of PCNSL to the CNS. Recombinant antibodies (recAb) identical with the BCR of a series of 23 PCNSL from immunocompetent patients.
Project description:Protein Ser/Thr kinase CK2 is involved in a myriad of cellular processes including cell growth and proliferation by phosphorylating hundreds of substrates, yet the regulation process of CK2 function is poorly understood. The CK2 catalytic subunit, CK2α, is phosphorylated at Thr344 and phosphorylation on the C-terminal tail of CK2α is required for interaction with Pin1 protein. The substrate selectivity for protein kinase CK2α was examined by performing kinase assays on protein microarrays spotted with 17,000 human proteins. Semisynthetic CK2α proteins were prepared to contain an unmodified C-terminal tail or phospho-Thr (pThr) at T344. These semisynthetic proteins were used to determine if the phosphorylation-dependent interaction of CK2α with Pin1 can modulate the substrate selectivity for CK2. The different semisynthetic CK2α proteins (unmodified and pThr344) were tested alone and in the presence of the recombinant Pin1 protein. Pin1 has been shown to interaction with CK2α only when CK2α is phoshorylated on its C-terminal site (including Thr344). In the study presented here, kinase assays were performed using two different semisynthetic CK2α proteins: unmodified C-terminal tail and phospho-Thr (pThr) at 344. The semisynthetic proteins were each tested alone and in the presence of the recombinant Pin1 protein. There were four different kinase conditions and each condition was performed in duplicate.
Project description:The pathogenesis of Chlamydophila (C.) psittaci negative ocular adnexal extranodal marginal zone lymphomas (OAEMZLs) is poorly understood. OAEMZLs are monoclonal tumors expressing a biased repertoire of mutated surface immunoglobulins. Antigenic activation of the B cell receptor (BCR) may play a role in the pathogenesis of these lymphomas. We have analyzed the reactivity of recombinant OAEMZL immunoglobulins. OAEMZL antibodies reacted with self-human antigens, as demonstrated by enzyme-linked immunosorbent assays, HEp-2 immunofluorescence and human protein microarrays. All the analyzed recombinant antibodies (rAbs) exhibited polyreactivity by comprehensive protein array antibody reactivity and some rAbs also demonstrated rheumatoid factor activity. The identity of several reactive antigens was confirmed by microcapillary reverse-phase HPLC nano-electrospray tandem mass spectrometry. The tested rAbs frequently reacted with shared intracellular and extracellular self-antigens (e.g. galectin-3). Furthermore, these self-antigens induced BCR signaling in B cells expressing cognate surface immunoglobulins derived from OAEMZLs. These findings suggest that interactions between self-antigens and cognate OAEMZL tumor-derived BCRs are functional, inducing intracellular signaling. Overall our findings suggest that self-antigen-induced BCR stimulation may be implicated in the pathogenesis of C. psittaci negative OAEMZLs. Antibody Specificity Profiling with four OAEMZL rAbs (Ab4438, Ab4726, Ab5334, and Ab11274) performed on ProtoArray Human Protein Microarrays