Dimer-dimer stacking interactions are important for nucleic acid binding by the archaeal chromatin protein Alba

Archaea use a variety of small basic proteins to package their DNA. One of the most widespread and highly conserved is the Alba (Sso10b) protein. Alba interacts with both DNA and RNA in vitro, and we show in the present study that it binds more tightly to dsDNA (double-stranded DNA) than to either ssDNA (single-stranded DNA) or RNA. The Alba protein is dimeric in solution, and forms distinct ordered complexes with DNA that have been visualized by electron microscopy studies; these studies suggest that, on binding dsDNA, the protein forms extended helical protein fibres. An end-to-end association of consecutive Alba dimers is suggested by the presence of a dimer-dimer interface in crystal structures of Alba from several species, and by the strong conservation of the interface residues, centred on Are and Phe(60). In the present study we map perturbation of the polypeptide backbone of Alba upon binding to DNA and RNA by NMR, and demonstrate the central role of Phe(60) in forming the dimer dimer interface. Site-directed spin labelling and pulsed ESR are used to confirm that an end-to-end, dimer dimer interaction forms in the presence of dsDNA.Publisher PDFPeer reviewe

Attribution in sport psychology: Seeking congruence between theory, research and practice

Objectives: This paper urges revision of the way attributions are conceptualised, investigated, and applied in sport psychology. There has been a recent decline in attribution research in sport psychology, despite the generally accepted relevance of attributions in applied settings. In seeking closer links between attribution theory, research, and practice, we argue that there is a mismatch between research and practice in sport psychology. Methods: Relevant literature is reviewed and theoretical arguments offered within seven sub-headings: Attribution theory in practice; linking consistency, distinctiveness, and consensus information to attribution dimensions; controllability as the primary attribution dimension; the generalisability of controllability; assessing attributions; implications for practice; and the social context. Results and conclusions: Research within sport psychology should focus on the central issue of how controllability attributions generalise across time, situations, and people. Measurement should reflect this approach to research within the field of attributions and, to this end, researchers might consider using a variety of quantitative and qualitative methods of inquiry. Practitioners should use consistency, distinctiveness, and consensus information to challenge clients' attributional thinking and help them attain adaptive perceptions of controllability. Practitioners should also help clients to be their own psychologist. Future research and practice should include a consideration of the social context in which attributions are shaped. © 2004 Elsevier Ltd. All rights reserved

Performance assessment in sport: Formulation, justification, and confirmatory factor analysis of a measurement instrument for tennis performance

publication-status: Publishedtypes: ArticleCopyright © 2000 Taylor & Francis. This is an Author's Accepted Manuscript of an article published in Journal of Applied Sport Psychology available online at: http://www.tandfonline.com/doi/abs/10.1080/10413200008404223#.VNnjyp1FDcsThe present study reports the refinement and confirmatory factor analysis of a performance assessment instrument designed for tennis, first reported in Pees, Ingledew, and Hardy (1999). Background and justification for this study are reported, together with a detailed description of the sequential model-testing approach (Joreskog, 1993) adopted. The factor structure of the instrument was tested using a sample of 155 full-time tennis players. Analyses revealed good fit for the proposed model to the new data sample, and provided confirmation for the seven performance factors: Execution of (Flexible) Plan, Loss of Composure, Feeling Flat, Determination, Worry, Flow, and Effective Tactics. Performance factors discriminated between winners and losers. Performers should look at the various factors comprising overall performance; in a sense, the processes by which they come to achieve their successes

Social support dimensions and components of performance in tennis.

types: Comparative Study; Journal ArticleCopyright © 1999 Taylor & Francis. This is an Author's Accepted Manuscript of an article published in Journal of Sports Sciences, 1999 Vol. 17, Issue 5, pp. 421 – 429 available online at: http://www.tandfonline.com/doi/abs/10.1080/026404199365948The aim of this study was to explore the relationships between dimensions of social support and components of performance in tennis. A post-match performance measure was completed by 144 British tournament tennis players. Principal components analysis yielded eight components, labelled Execution of (Flexible) Plan, Loss of Composure, Feeling Flat, Positive Tension, Worry, Flow, Effective Tactics and Double Faults. Before the match, 46 players had also completed the Interpersonal Support Evaluation List. Stepwise regression analyses revealed significant effects of the Belonging and Appraisal dimensions of the Interpersonal Support Evaluation List on five of the performance components. The correlations between total support and four of these performance components were also significant. Logistic regression analyses revealed no significant effects of the dimensions of the Interpersonal Support Evaluation List or Total Support upon winning versus losing. Effects of social support upon performance were therefore only apparent when attention was focused on the components of performance

In the zone: an exploration of personal characteristics underlying affective responses to heavy exercise

Positive affective responses to exercise have been linked with longer term adherence. The Dual-Mode Model indicates that affective responses during heavy exercise (between the ventilatory threshold and the respiratory compensation point) are subject to interindividual variability (zone of response variability). Participants (N = 48) completed measures to assess personal characteristics prior to a graded exercise test (GXT). Responses to the Feeling Scale were recorded during the GXT and subsequently used to group participants as either Negative Responders or Neutral/Positive Responders to heavy exercise. Discriminant Function Analysis was applied and a significant weighted linear composite predicted affective response. Preference for exercise intensity and sex were significant predictors (p = .003). Negative Responders had lower Preference scores and were more likely to be men. The combination of these two variables successfully predicted group membership 71% of the time. Individual differences appear relevant when examining affective responses to heavy exercise

Elucidating the Roles of Motives and Gains in Exercise Participation

Previous research into the role of exercise motives (what people want from exercise) has overlooked the possible role of gains (what people get) and hence the possible benefits of motive fulfillment (when people get what they want). To redress this imbalance, we examined the additive and interactive effects of motives and subjective gains on exercise-specific outcomes. Young adults (N = 196) completed measures of exercise motives and gains, and exercise behavioral regulation, amount, satisfaction, and intention. Four representative motives/gains were selected: appearance, positive health, challenge, and affiliation. Path analysis was used to test the effects of motives, gains, and their products (the interactive effects) on behavioral regulations, and thereby exercise amount, satisfaction, and intention. Controlled regulation increased with appearance motive, unless appearance gain was high. Controlled regulation had a negative effect on exercise satisfaction. Autonomous regulation increased with positive health motive, provided positive health gain was high; with challenge motive and gain; and with affiliation motive. Autonomous regulation had positive effects on exercise amount, satisfaction, and intention. The study corroborates previous findings about the effects of motives. It establishes the value of also studying gains, as moderators of the effects of motives, and in their own right. The findings are interpretable in terms of self-determination theory. Exercise promotion could be more effective if it focused on gains in conjunction with motives

Effects of motives on reactions to safe sun messages

We investigated whether appearance motive for sun exposure, which strongly predicts exposure behaviour, would predict reactions to safe sun messages. In a survey with an embedded experiment, 245 individuals completed measures of motives, read a safe sun message framed by incentive (appearance/health), tone (directive/nondirective) and valence (gain/loss), then completed measures of reactions. For participants high in appearance motive, an appearance-nondirective message was most persuasive. Regardless of individual's appearance motive, appearance messages produced lower reactance if phrased using nondirective language. To maximise persuasion and minimise reactance in individuals most motivated to sun expose, safe sun messages should focus on appearance using nondirective language