Dissecting the role of conformational change and membrane binding by the bacterial cell division regulator MinE in the stimulation of MinD ATPase activity.

The bacterial cell division regulators MinD and MinE together with the division inhibitor MinC localize to the membrane in concentrated zones undergoing coordinated pole-to-pole oscillation to help ensure that the cytokinetic division septum forms only at the mid-cell position. This dynamic localization is driven by MinD-catalyzed ATP hydrolysis, stimulated by interactions with MinE's anti-MinCD domain. This domain is buried in the 6-ß-stranded MinE "closed" structure, but is liberated for interactions with MinD, giving rise to a 4-ß-stranded "open" structure through an unknown mechanism. Here we show that MinE-membrane interactions induce a structural change into a state resembling the open conformation. However, MinE mutants lacking the MinE membrane-targeting sequence stimulated higher ATP hydrolysis rates than the full-length protein, indicating that binding to MinD is sufficient to trigger this conformational transition in MinE. In contrast, conformational change between the open and closed states did not affect stimulation of ATP hydrolysis rates in the absence of membrane binding, although the MinD-binding residue Ile-25 is critical for this conformational transition. We therefore propose an updated model where MinE is brought to the membrane through interactions with MinD. After stimulation of ATP hydrolysis, MinE remains bound to the membrane in a state that does not catalyze additional rounds of ATP hydrolysis. Although the molecular basis for this inhibited state is unknown, previous observations of higher-order MinE self-association may explain this inhibition. Overall, our findings have general implications for Min protein oscillation cycles, including those that regulate cell division in bacterial pathogens.

An investigation into human pandemic influenza virus (H1N1) 2009 on an Alberta swine farm.

On May 2, 2009 the Canadian Food Inspection Agency notified the World Organization for Animal Health that an emerging novel influenza A virus (pandemic H1N1 2009) had been confirmed on a swine farm in Alberta. Over a 4-week period pigs in this farrow-to-finish operation were clinically affected by respiratory disease consistent with an influenza A virus infection and the presence of active viral infection was confirmed in all production areas by real-time polymerase chain reaction (RT-PCR). Despite clinical recovery of animals, there was reluctance by purchasers to receive animals from this operation due to concerns about the effect on both domestic and international markets. The owner decided to depopulate the entire herd due to impending welfare issues associated with overcrowding and economic concerns resulting from the inability to market these animals. Carcasses were rendered or composted and did not enter the human food or animal feed chain. The source of virus in this herd was determined to be an infected human. Zoonotic transmission to 2 individuals responding to the outbreak was suspected and recommendations to prevent occupational exposure are discussed.

The effects of a supplemental, theory-based physical activity counseling intervention for adults with type 2 diabetes.

BACKGROUND: Physical activity (PA) is a cornerstone in the management of type 2 diabetes (T2DM). This pilot investigation explores the effects of a standard diabetes education program compared with a supplemental PA intervention on diabetes-related health outcomes. METHODS: Using a prospective 2-armed design, 96 adults with T2DM were randomly assigned to either standard care (diabetes education program; n = 49) or standard care supplemented with an 8-week, individualized-counseling and community-based PA component (n = 47). Measurements were taken at baseline, 3, 6, and 12 months. Primary outcomes were changes in PA (self-report) and HbA1c. Between group changes were compared using analysis of covariance (ANCOVA) and changes over time using repeated-measures ANOVA. RESULTS: In comparison with standard care, the supplemental group demonstrated an increase in PA (Ps < 0.01) and cardiorespiratory fitness (Ps < 0.05) from baseline to all follow-up time-points. HbA1c levels declined (P < .05) from baseline to all time points in the standard care group. Reduction in cholesterol-ratio (P < .01), increase in HDL (P < .05), and reductions in blood pressure, resting heart rate and BMI (approaching statistical significance Ps < 0.10) were also reported for both groups. CONCLUSIONS: PA counseling in addition to standard care is effective for promoting PA behavior change and positive health-related outcomes among individuals with T2DM.