Migfilin, a molecular switch in regulation of integrin activation.

The linkage of heterodimeric (alpha/beta) integrin receptors with their extracellular matrix ligands and intracellular actin cytoskeleton is a fundamental step for controlling cell adhesion and migration. Binding of the actin-linking protein, talin, to integrin beta cytoplasmic tails (CTs) induces high affinity ligand binding (integrin activation), whereas binding of another actin-linking protein, filamin, to the integrin beta CTs negatively regulates this process by blocking the talin-integrin interaction. Here we show structurally that migfilin, a novel cytoskeletal adaptor highly enriched in the integrin adhesion sites, strongly interacts with the same region in filamin where integrin beta CTs bind.

Molecular basis for PKR activation by PACT or dsRNA.

The mammalian protein kinase PKR is a critical component of the innate immune response against virus infection. Its cellular actions are mediated by modulating cell signaling and translational regulation. To be enzymatically active, latent PKR needs to be activated by binding to one of its activators, dsRNA or PACT protein.

Three-dimensional correlated accordion NMR spectroscopy of proteins.

A major step toward the protein structure determination by nuclear magnetic resonance (NMR) spectroscopy is the assignment of multidimensional NMR signals that provide through-bond and through-space inter-atomic correlations. Ambiguities often occur during the assignment process due to resonance degeneracy, which challenges high resolution and larger size protein structure determination. Here, we present a method that will significantly improve the efficiency and accuracy of the NMR signal assignment.

Protein Backbone 1H(N)-13Calpha and 15N-13Calpha residual dipolar and J couplings: new constraints for NMR structure determination.

A simple, sensitivity-enhanced experiment was devised for accurate measurement of backbone 15N-13Calpha and 1HN-13Calpha couplings in proteins. The measured residual dipolar couplings 2DHCA, 1DNCA, 3DHCA, and 2DNCA for protein GB1 display very good agreement with the refined NMR structure (PDB code: 3GB1). A Karplus-type relationship between the one-bond 1JNCA couplings and the backbone dihedral psi angles holds, and on the basis of the two-bond 2JNCA couplings a secondary structure index can be established.

Sensitivity-enhanced IPAP experiments for measuring one-bond 13C'-13Calpha and 13Calpha-1Halpha residual dipolar couplings in proteins.

Sensitivity-enhanced 2D IPAP experiments using the accordion principle for measuring one-bond 13C'-13Calpha and 1Halpha-13Calpha dipolar couplings in proteins are presented. The resolution of the resulting spectra is identical to that of the decoupled HSQC spectra and the sensitivity of the corresponding 1D acquisitions are only slightly lower than those obtained with 3D HNCO and 3D HN(COCA)HA pulse sequences due to an additional delay 2Delta. For cases of limited resolution in the 2D 15N-1HN HSQC spectrum the current pulse sequences can easily be modified into 3D versions by introducing a poorly digitized third dimension, if so desired.

Insights into conformation and dynamics of protein GB1 during folding and unfolding by NMR.

Understanding protein stability requires characterization of structural determinants of the folded and unfolded states. Many proteins are capable of populating partially folded states under specific solution conditions. Occasionally, coexistence of the folded and an unfolded state under non- or mildly denaturing conditions can be observed by NMR, allowing us to structurally probe these states under identical conditions.

Simultaneous and accurate determination of one-bond (15)N-(13)C' and two-bond (1)H(N)--(13)C' dipolar couplings.

Using the echo-anti-echo manipulation, the 15N-1HN cross-peaks split in the E.COSY spectrum by the 13CO couplings are separated into different, distinct regions in the HSQC spectrum. From this novel E.

Sensitivity-enhanced 2D IPAP, TROSY-anti-TROSY, and E.COSY experiments: alternatives for measuring dipolar 15N-1HN couplings.

Sensitivity-enhanced versions of the IPAP, TROSY-anti-TROSY, and E.COSY experiments for measuring one-bond 15N-1HN couplings are presented. Together with the previously developed sensitivity-enhanced E.

Reduction of pentavalent antimony by trypanothione and formation of a binary and ternary complex of antimony(III) and trypanothione.

Several pentavalent antimony compounds have been used for the treatment of leishmaniasis for decades. However, the mechanism of these antimony drugs still remains unclear. One of their targets is thought to be trypanothione, a major low molecular mass thiol inside the parasite.

Sensitivity-enhanced E.COSY-type HSQC experiments for accurate measurements of one-bond 15N-1H(N) and 15N-13C' and two-bond 13C'-1H(N) residual dipolar couplings in proteins.

Novel E.COSY-type HSQC experiments are presented for the accurate measurement of one-bond 15N-1H(N) and 15N-13C(') and two-bond 13C(')-1H(N) residual dipolar couplings in proteins. Compared with existing experiments, the (delta,J)-E.

Novel 2D triple-resonance NMR experiments for sequential resonance assignments of proteins.

We present 2D versions of the popular triple resonance HN(CO) CACB, HN(COCA)CACB, HN(CO)CAHA, and HN(COCA) CAHA experiments, commonly used for sequential resonance assignments of proteins. These experiments provide information about correlations between amino proton and nitrogen chemical shifts and the alpha- and beta-carbon and alpha-proton chemical shifts within and between amino acid residues. Using these 2D spectra, sequential resonance assignments of H(N), N, C(alpha), C(beta), and H(alpha) nuclei are easily achieved.