Characterization of attB and core-attP recombination sites of the integrase from Lactobacilus delbrueckii subsp. bulgaricus bacteriophage mv4
Ontology highlight
ABSTRACT: Different attB or attP DNA libraries containing 7-bp random nucleotides were used for in vitro recombination mediated by the purified integrase from mv4 bacteriophage against their cognate wild-type attB or attP recombination site.
Project description:Cross-linking of living cells followed by mass spectrometry identification of cross-linked peptides (in situ CLMS) is an emerging technology to study protein structures in their native environment. One of the inherent difficulties of this approach is the high complexity of the samples following cell lysis. This difficulty largely limits the identification of cross-links to the more abundant proteins in the cell. Here, we describe a targeted approach in which an antibody pulls a specific protein-of-interest out of the lysate. Mass spectrometry analysis of the protein material that binds to the antibody can then identify considerably more cross-links on the antibody target and its interactors. By using an antibody against the CCT chaperonin, we obtained over two hundred cross-links that provide in situ evidence for the subunit arrangement of CCT and its main interactions with prefoldin. Antibodies against tubulin likewise provided in situ evidence for the structure of the microtubule including the seam. Finally, the approach was also successful in identifying cross-links on a protein expressing at very low amounts (tau in non-neuronal cells). These results demonstrate the general applicability of antibody-based sample simplification for in situ CLMS.
Project description:The intrinsically disordered protein, α-synuclein, implicated in synaptic vesicle homeostasis and neurotransmitter release, is also associated with several neurodegenerative diseases. The different roles of α-synuclein are characterized by distinct structural states (membrane-bound, dimer, tetramer, oligomer, and fibril), which are originated from its various monomeric conformations. The pathological states, determined by the ensemble of α-synuclein monomer conformations and dynamic pathways of interconversion between dominant states, remain elusive due to their transient nature. Here, we use inter-dye distance distributions from bulk time-resolved Förster resonance energy transfer as restraints in discrete molecular dynamics simulations to map the conformational space of the α-synuclein monomer. We further confirm the generated conformational ensemble in orthogonal experiments utilizing far-UV circular dichroism and cross-linking mass spectrometry. Single-molecule protein-induced fluorescence enhancement measurements show that within this conformational ensemble, some of the conformations of αsynuclein are surprisingly stable, exhibiting conformational transitions slower than milliseconds. Our comprehensive analysis of the conformational ensemble reveals essential structural properties and potential conformations that promote its various functions in membrane interaction or oligomer and fibril formation.
Project description:Formaldehyde is a widely used fixative in biology and medicine. The current chemical model for formaldehyde cross-linking of proteins is the formation of a methylene bridge that incorporates one carbon atom into the link. Here, we present mass spectrometry data that largely refute this model. Instead, our data show that cross-linking of structured proteins mainly involves a reaction that incorporates two carbon atoms into the link. Under MS/MS fragmentation, the link cleaves symmetrically to yield unusual fragments with a modification of one carbon atom. We apply this new understanding of the underlying cross-linking chemistry to the structural approach of cross-linking coupled to mass spectrometry. First, we cross-linked a mixture of purified proteins with formaldehyde. Our new analysis readily identified tens of cross-links from these proteins, which fit well with their atomic structures. We then perform in-situ cross-linking of human cells in culture. We identified 469 intra-protein and 90 inter-protein cross-links, which also fit well with available atomic structures. Interestingly, many of these cross-links could not be mapped onto a known structure and thus provide new structural insights. We highlight an example in which formaldehyde cross-links localize the binding site of βNAC on the ribosome. We also find several interactions of actin with auxiliary proteins. Our findings not only expand our understanding of formaldehyde reactivity and toxicity, but also clearly demonstrate how to use this potent reagent for structural studies.
Project description:We analyzed the proteome of mouse FACS-sorted podocytes. We compared podocytes ("green cells") with non-podocyte ("red cells") cells of the glomerulus.
Project description:APEX was targeted to the primary cilium of mouse IMCD cells using a 5HT6-APEX-GFP fusion construct. Proximity labling was performed using incubation with biotinphenol and H2O2. For details, please see the methods section of the accompanying paper.
Project description:The aim of this project was to detect phosphorylation on the human calcium Channel TRPC6. TRPC6 is mutated in genetic diseases of the podocyte, a postmitotic cell at the epithelial filtration barrier
Project description:Overexpression of SOX4 in LN229 glioblastoma cells prevents their cell cycle Examination of SOX4 binding profile in prostate cell LN229-SOX4 with LN229-GFP as negative control.
Project description:Background: Members of E. coli serogroup O45 are porcine enteropathogenic E. coli (PEPEC) strains which cause post-weaning diarrhea and produce characteristic attaching and effacing (A/E) lesions. Most of O45 PEPEC strains possess the locus of enterocyte effacement (LEE), encoding the virulence factors for A/E lesions, and often possess the paa gene, which is thought to contribute to the early stages of PEPEC virulence. Methodology: Nine O45 PEPEC strains and a rabbit enteropathogenic (REPEC) strain, known to produce A/E lesions, were characterized using an E. coli O157-E. coli K12 whole genome microarray and a virulence gene-specific microarray, and by PCR experiments. Results: Based on their virulence genes profiles, the 10 strains were characterized as atypical EPEC. The differences in their genomes pointed to two distinct evolutionary groups of O45 PEPEC, Group I and Group II, and to the contribution these genetic differences have on virulence in pigs. Group I contained the REPEC strain and four O45 PEPEC strains known to induce severe A/E lesions in challenged pigs whereas Group II was composed of five other O45 PEPEC strains which induced less severe or no A/E lesions in challenged pigs. Significant differences between Groups I and II were found in the presence or absence of 50 O-Islands (OIs) or S-loops and 13 K-islands (KIs) or K-loops, including the virulence-associated islands OI#1 (S-loop#1), OI#47 (S-loop#71), OI#57 (S-loop#85), OI#71 (S-loop#108), OI#115, OI#122, and OI#154 (S-loop#253). 10 samples, with two microarrays per sample. Each microarray includes duplicates of every spot.