The tetratricopeptide repeat: A structural motif mediating protein-protein interactions

The tetratricopeptide repeat (TPR) motif is a protein-protein interaction module found in multiple copies in a number of functionally different proteins that facilitates specific interactions with a partner protein(s). Three-dimensional structural data have shown that a TPR motif contains two antiparallel a-helices such that tandem arrays of TPR motifs generate a right-handed helical structure with an amphipathic channel that might accommodate the complementary region of a target protein. Most TPR-containing proteins are associated with multiprotein complexes, and there is extensive evidence indicating that TPR motifs are important to the functioning of chaperone, cell-cycle, transcription, and protein transport complexes. The TPR motif may represent an ancient protein-protein interaction module that has been recruited by different proteins and adapted for specific functions

The social Interview Schedule (SIS) - context, structure and reliability

The English original form of a standardized social interview was presented by Clare and Cairns (1978). The German version is described with regard to concept, structure, and methodology. The interview is designed to assess social maladjustment by measuring three conceptual categories (“Objective Material Conditions,” “Social Management,” and “Satisfaction”) in eight role areas. The instrument is especially suited for outcome assessment in various clinical and non-clinical populations and takes an average of about 30–45 min to complete. The 39 items are rated on 4-point scales either by the interviewer with the help of an extensive rating manual, or by the subject himself (all “Satisfaction” items). The results of a reliability study are presented using both the test-retest and the interrater method. In general, the results show that the instrument is satisfactorily reliable, but some possible weaknesses are discussed. Finally, the structure of the instrument is examined by an analysis of interrelationships between the items in a normal population sample. The results are discussed with regard to questions of score construction

Isolation of a mouse cDNA encoding mSTI1, a stress-inducible protein containing the TPR motif

We report the isolation and sequencing of the complete 2079-bp cDNA fragment encoding mSTI1, a murine stress-inducible protein. The predicted ORF encodes a protein of 543 amino acids (aa) and Mr 62 582. The predicted protein has significant homology to stress-inducible proteins from humans (IEF SSP 3521), soybean (GMSTI), yeast (STI1) and a parasite, Leishmania donovani (LSIP). All of these proteins contain 34-aa repeat motifs, termed tetratricopeptide repeats (TPRs), that are proposed to be involved in intra- and intermolecular protein interactions. mSTI1 has ten potential TPR motifs, a putative nuclear localization signal (NLS), six potential phosphorylation sites for casein kinase II and a central proline-rich region. Western analysis detected a protein of approx. 63 kDa in all the major mouse organs and in mouse, monkey and human cell lines

The DECON pilot project investigates predictive markers for successful bariatric surgery

Abstract Obesity is a chronic, multifactorial disease which is linked to a number of adverse endocrinological and metabolic conditions. Currently, bariatric surgery is one of the most effective treatments for individuals diagnosed with severe obesity. However, the current indications for bariatric surgery are based on inadequate metrics (i.e., BMI) which do not account for the complexity of the disease, nor the heterogeneity among the patient population. Moreover, there is a lack of understanding with respect to the biological underpinnings that influence successful and sustained weight loss post-bariatric surgery. Studies have implicated age and pre-surgery body weight as two factors that are associated with favorable patient outcomes. Still, there is an urgent medical need to identify other potential factors that could improve the specificity of candidate selection and better inform the treatment plan of patients with obesity. In this report, we present and describe the cohort of the DECON pilot project, a multicenter study which aims to identify predictive biomarkers of successful weight loss after bariatric surgery

The cochaperone murine stress-inducible protein 1: overexpression, purification, and characterization

Murine stress-inducible protein 1 (mSTI1) is a cochaperone that is homologous with the human heat shock cognate protein 70 (Hsc70)/heat shock protein 90 (Hsp90)-organizing protein (Hop). To analyze the biochemical properties of mSTI1 and the stoichiometry of the Hsc70.mSTI1.Hsp90 association, recombinant mSTI1 was produced in untagged, histidine (His)-tagged, and glutathione S-transferase (GST)-tagged forms. His-mSTI1 was detected either as a dimer during size-exclusion-high-performance liquid chromatography (SE-HPLC) or as a monomer during Superdex 200 gel filtration chromatography. SE-HPLC on GST-mSTI1 and untagged mSTI1 suggested that mSTI1 existed as a monomer. Cross-linking of His-mSTI1 detected a compact monomeric species and a dimeric species. Gel filtration on the association of bovine STI1 or His-mSTI1 with Hsc70 detected species of molecular mass consistent with a dimeric STI1 species or a 1:1 complex of STI1 and Hsc70. Our data and that of others suggest that mSTI1 and its homologues exist as either a monomer or a dimer and that this facilitates its proposed function as an Hsc70/Hsp90 organizing protein

Electrostatic Interactions of Hsp-organizing Protein Tetratricopeptide Domains with Hsp70 and Hsp90: COMPUTATIONAL ANALYSIS AND PROTEIN ENGINEERING

The Hsp-organizing protein (HOP) binds to the C termini of the chaperones Hsp70 and Hsp90, thus bringing them together so that substrate proteins can be passed from Hsp70 to Hsp90. Because Hsp90 is essential for the correct folding and maturation of many oncogenic proteins, it has become a significant target for anti-cancer drug design. HOP binds to Hsp70 and Hsp90 via two independent tetratricopeptide (TPR) domains, TPR1 and TPR2A, respectively. We have analyzed ligand binding using Poisson-Boltzmann continuum electrostatic calculations, free energy perturbation, molecular dynamics simulations, and site-directed mutagenesis to delineate the contribution of different interactions to the affinity and specificity of the TPR-peptide interactions. We found that continuum electrostatic calculations could be used to guide protein design by removing unfavorable interactions to increase binding affinity, with an 80-fold increase in affinity for TPR2A. Contributions at buried charged residues, however, were better predicted by free energy perturbation calculations. We suggest using a combination of the two approaches for increasing the accuracy of results, with free energy perturbation calculations used only at selected buried residues of the ligand binding pocket. Finally we present the crystal structure of TPR2A in complex with its non-cognate Hsp70 ligand, which provides insight on the origins of specificity in TPR domain-peptide recognition