Dynamic effects of cofactors and DNA on the oligomeric state of human mitochondrial DNA helicase

We examined the effects of cofactors and DNA on the stability, oligomeric state and conformation of the human mitochondrial DNA helicase. We demonstrate that low salt conditions result in protein aggregation that may cause dissociation of oligomeric structure. The low salt sensitivity of the mitochondrial DNA helicase is mitigated by the presence of magnesium, nucleotide, and increased temperature. Electron microscopic and glutaraldehyde cross-linking analyses provide the first evidence of a heptameric oligomer and its interconversion from a hexameric form. Limited proteolysis by trypsin shows that binding of nucleoside triphosphate produces a conformational change that is distinct from the conformation observed in the presence of nucleoside diphosphate. We find that single-stranded DNA binding occurs in the absence of cofactors and renders the mitochondrial DNA helicase more susceptible to proteolytic digestion. Our studies indicate that the human mitochondrial DNA helicase shares basic properties with the SF4 replicative helicases, but also identify common features with helicases outside the superfamily, including dynamic conformations similar to other AAA⁺ ATPases.

Improving bilingual higher education: Training university professors in content and language integrated learning

With increasing international mobility, higher education must cater to the varying linguistic and cultural needs of students. Successful delivery of courses through English as the vehicular language is essential to encourage international enrollment. However, this cannot be achieved without preparing university professors in the many intricacies delivering their subjects in English may pose. This paper aims to: share preliminary data concerning Content and Language Integrated Learning (CLIL) at Laureate Network Universities worldwide as few studies have been conducted at the tertiary level, reflect upon data regarding student and teacher satisfaction with CLIL at the Universidad Europea de Madrid (UEM), and to propose improvements in English-taught subjects.