The oncoprotein E7 of human papilloma viruses (HPV) is involved in the pathogenesis and maintenance of human cervical cancers. The most prevalent HPV types found in cervix carcinomas are HPV16, 18 and 45. The structure of the E7 dimer from HPV45 (PDB 2F8B) was determined by nuclear magnetic resonance spectroscopy. Each monomer comprises an unfolded N-terminus and a well-structured C-terminal domain with a b1b2a1b3a2 topology representing a unique zinc-binding fold found only for E7. Dimerization occurs through the a1/a1 0 helices and intermolecular b-sheet formation but excludes the zinc-binding sites. E7 is reported to interact with a number of cellular proteins (e.g. pRb, p21 CIP1 ). Binding of a peptide derived from the C-terminus of p21CIP1 to the Cterminal domain of E7 was characterized by monitoring chemical shift perturbations of the amide groups of E7. This provides direct evidence that a shallow groove situated between a1 and b1 of the E7 C-terminal domain is interacting with the C-terminus of p21
CIP1. Intriguingly, this binding site overlaps with the low-affinity binding site on E7 for the C-domain of pRb.
Learn about Alzheimer: The molecular conformation of a toxic β‐amyloid oligomer structure was determined by NMR spectroscopy (see picture). The measurements show a N‐terminal β strand that controls the partitioning between oligomer and protofibril formation. Targeting the N‐terminus of the peptide neutralizes Aβ‐dependent neuronal dysfunctions. The data have important implications for understanding the structural basis of Alzheimer's disease.
Stemloop D (SLD) of the 5' cloverleaf RNA is the cognate ligand of the coxsackievirus B3 (CVB3) 3C proteinase (3Cpro). Both are indispensable components of the viral replication initiation complex. SLD is a structurally autonomous subunit of the 5' cloverleaf. The SLD structure was solved by NMR spectroscopy to an rms deviation of 0.66 A (all heavy atoms). SLD contains a novel triple pyrimidine mismatch motif with a central Watson-Crick type C:U pair. SLD is capped by an apical uCACGg tetraloop adopting a structure highly similar to stable cUNCGg tetraloops. Binding of CVB3 3Cpro induces changes in NMR spectra for nucleotides adjacent to the triple pyrimidine mismatch and of the tetraloop implying them as sites of specific SLD:3Cpro interaction. The binding of 3Cpro to SLD requires the integrity of those structural elements, strongly suggesting that 3Cpro recognizes a structural motif instead of a specific sequence.
We have carried out chemical shift correlation experiments with symmetry-based mixing sequences at high MAS frequencies and examined different strategies to simultaneously acquire 3D correlation spectra that are commonly required in the structural studies of proteins. The potential of numerically optimised symmetry-based mixing sequences and the simultaneous recording of chemical shift correlation spectra such as: 3D NCAC and 3D NHH with dual receivers, 3D NC'C and 3D C'NCA with sequential (13)C acquisitions, 3D NHH and 3D NC'H with sequential (1)H acquisitions and 3D CANH and 3D C'NH with broadband (13)C-(15)N mixing are demonstrated using microcrystalline samples of the β1 immunoglobulin binding domain of protein G (GB1) and the chicken α-spectrin SH3 domain.
Stemloop D (SLD) of the 5' cloverleaf RNA is the cognate ligand of the coxsackievirus B3 (CVB3) 3C proteinase (3Cpro). Both are indispensable components of the viral replication initiation complex. SLD is a structurally autonomous subunit of the 5' cloverleaf. The SLD structure was solved by NMR spectroscopy to an rms deviation of 0.66 A (all heavy atoms). SLD contains a novel triple pyrimidine mismatch motif with a central Watson-Crick type C:U pair. SLD is capped by an apical uCACGg tetraloop adopting a structure highly similar to stable cUNCGg tetraloops. Binding of CVB3 3Cpro induces changes in NMR spectra for nucleotides adjacent to the triple pyrimidine mismatch and of the tetraloop implying them as sites of specific SLD:3Cpro interaction. The binding of 3Cpro to SLD requires the integrity of those structural elements, strongly suggesting that 3Cpro recognizes a structural motif instead of a specific sequence.
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