Proton and nitrogen NMR sequence-specific assignments and secondary structure determination of the Bacillus subtilis SPO1-encoded transcription factor 1.

Sequence-specific 1H and 15N NMR1 assignments are reported for the transcription factor 1 (TF1), a 22-kDa type II DNA-binding protein (DBPII) that consists of two 99-residue monomers. An assignment strategy is employed that uses six complementary selectively deuterium-labeled TF1 variants and an uniformly 15N-labeled TF1 variant. Two-dimensional and three-dimensional homonuclear and heteronuclear NMR correlated spectra are analyzed and yield nearly complete assignments for the 1H and 15N resonances. Discrete protein secondary structure domains are also defined; in each monomer, three alpha-helices, an antiparallel beta-sheet, and an antiparallel beta-ribbon are identified. Analyses of two dimers formed from two distinct selectively deuteriated monomers serve to identify a number of interproton contacts as either intermonomeric or intramonomeric. An analysis of amide proton exchange reveals that the carboxy-terminal alpha-helix is less stable than the other two alpha-helices in each monomer. A previously proposed working structural model of the TF1 dimer [Geiduschek et al. (1990) J. Struct. Biol. 104, 84-90], based on the crystal structure of a highly homologous DBPII, the Bacillus stearothermophilus-encoded HU protein, is generally supported by our results. Several departures from this model, however, are noted. Most notably, the carboxy-terminal tail of TF1 adopts an alpha-helical conformation with a backbone distortion at Lys93.

A 1H-NMR study of the transcription factor 1 from Bacillus subtilis phage SPO1 by selective 2H-labeling. Complete assignment and structural analysis of the aromatic resonances for a 22-kDa homodimer.

1H-NMR experiments have been performed on transcription factor 1 (TF1) encoded by Bacillus subtilis phage SPO1. To study this 22-kDa homodimeric DNA-binding protein, a selective 2H-labeling strategy has been employed. Complete sequence-specific assignments of all the resonances from the five aromatic residues were determined by a modified standard sequential-assignment procedure. The reduced contribution of spin diffusion upon the long-mixing-time nuclear-Overhauser-enhancement spectroscopy for the selectively 2H-labeled variants, as opposed to the fully 1H-containing protein, has allowed for the identification of the spin systems and of the long-range dipolar contacts between Phe28 and Phe47 protons in the protein core and between Phe61 and Phe97 protons. The latter suggests an interaction between the proposed beta-ribbon DNA-binding arm and the carboxy terminus of the paired monomer. A previously proposed TF1 structural model [Geiduschek, E. P., Schneider, G. J. & Sayre, M. H. (1990) J. Struct. Biol. 104, 84-90)] has been modified using constrained-energy-minimization calculations incorporating the experimentally determined set of aromatic-to-aromatic contacts. This new model has been analyzed with regard to the relative mobility and the relative solvent accessibility of the aromatic residues which have been measured by the nonselective T1 relaxation times of the aromatic resonances for the fully 1H-containing protein and the relaxation time enhancements upon selective 2H-labeling, respectively.

An indirect measure of the value of friendship for aging men.

The purpose of this study was to assess the value of friendship for a group of aging men. From the 25th and the 50th Anniversary Report of the Harvard Class of 1930, 706 and 455 autobiographical sketches respectively, were analyzed for mentions of career, marital relationships, and friendship. The results indicated that married men value friendship significantly less than career or family. There was evidence of an increase in casual friendly relations with more leisure time in old age, but no indication of an increase in close friendships. These results are tempered by evidence of a broadened understanding of what constitutes friendship in adulthood.

SACRAL: toward the meaning and measurement of friendliness.

Friendliness was regarded as a construct or dispositional tendency consisting of four components: Self-concept (S), the person's beliefs about self related to peer relationships; Accessibility (AC), giving behaviors involving attention and respect; Rewardingness (R), the giving of more tangible rewards, such as money and compliments; and Alienation (AL), personal beliefs about acceptance and the world as a friendly place. A 40-item questionnaire was developed to assess these components of friendliness. Studies of the questionnaire with college students and children supported its internal consistency, test-retest reliability, concurrent validity, construct validity, and discriminant validity. Although virtually all respondents reported themselves as friendly, high SACRAL scorers, when compared with low scorers, less frequently experience loneliness and in a variety of contexts claim to be more apt to engage in friendly behaviors. The impression that emerges of relatively low scorers on SACRAL is of people whose professed actions are somewhat inconsistent with their personal beliefs.