A Cooperative Action of the ATP-Dependent Import Motor Complex and the Inner Membrane Potential Drives Mitochondrial Preprotein Import

The import of mitochondrial preproteins requires an electric potential across the inner membrane and the hydrolysis of ATP in the matrix. We assessed the contributions of the two energy sources to the translocation driving force responsible for movement of the polypeptide chain through the translocation channel and the unfolding of preprotein domains. The import-driving activity was directly analyzed by the determination of the protease resistances of saturating amounts of membrane-spanning translocation intermediates. The ability to generate a strong translocation-driving force was solely dependent on the activity of the ATP-dependent import motor complex in the matrix. For a sustained import-driving activity on the preprotein in transit, an unstructured N-terminal segment of more than 70 to 80 amino acid residues was required. The electric potential of the inner membrane was required to maintain the import-driving activity at a high level. The electrophoretic force of the potential exhibited only a limited capacity to unfold preprotein domains. We conclude that the membrane potential increases the probability of a dynamic interaction of the preprotein with the import motor. Polypeptide translocation and unfolding are mainly driven by the inward-directed translocation activity based on the functional cooperation of the import motor components

Increasing social disparities in obesity among 15000 pre-schoolers in a German district from 2009 to 2019

Background: Although childhood obesity prevalence has stagnated in many high-income regions after decades of increase, it continues to be a major public health problem with adverse effects. The objective was to examine obesity trends as a function of parental social status to identify obesity disparities among children. Methods: Data from school entry examinations from 2009 to 2019 of 14 952 pre-schoolers in one German district were used. Logistic regression models (obesity/overweight as dependent variable) and a linear regression [BMI z-score (BMIz) as dependent variable] were performed adjusted for social status and sex to investigate time trends in overweight and obesity. Results: Overall, we found an increase of obesity over time [odds ratio (ORs): 1.03 per year, 95% CI: 1.01–1.06]. Children with low social status had an OR of 1.08 per year (95% CI: 1.03–1.13), while the trend was less expressed in children with high social status (OR: 1.03 per year, 95% CI: 0.98–1.08). The mean BMIz decreased per year (regression coefficient −0.005 per year, 95% CI: −0.01 to 0.0) when considering all children. This decrease was more pronounced in children with high social status (regression coefficient: −0.011 per year, 95% CI: −0.019 to −0.004), compared with a slight increase of 0.014 (95% CI: −0.003 to 0.03) per year among children with low social status. Also, children with low parental social status were heavier and smaller than their peers with high social status. Conclusions: Although the mean BMIz decreased among pre-schoolers, obesity prevalence and status-related inequity in obesity prevalence increased from 2009 to 2019 in the region studied