Mitochondrial respirasome works as a single unit and the cross-talk between complexes I, III2 and IV stimulates NADH dehydrogenase activity.

Ustilago maydis is an aerobic basidiomycete that depends on oxidative phosphorylation for its ATP supply, pointing to the mitochondrion as a key player in its energy metabolism. Mitochondrial respiratory complexes I, III2, and IV occur in supramolecular structures named respirasome. In this work, we characterized the subunit composition and the kinetics of NADH:Q oxidoreductase activity of the digitonine-solubilized respirasome (1600 kDa) and the free-complex I (990 kDa). In the presence of 2,6-dimethoxy-1,4-benzoquinone (DBQ) and cytochrome c, both the respirasome NADH:O2 and the NADH:DBQ oxidoreductase activities were inhibited by rotenone, antimycin A or cyanide. A value of 2.4 for the NADH oxidized/oxygen reduced ratio was determined for the respirasome activity, while ROS production was less than 0.001% of the oxygen consumption rate. Analysis of the NADH:DBQ oxidoreductase activity showed that respirasome was 3-times more active and showed higher affinity than free-complex I. The results suggest that the contacts between complexes I, III2 and IV in the respirasome increase the catalytic efficiency of complex I and regulate its activity to prevent ROS production.

Patrones de susceptibilidad de gramnegativos en un hospital pediátrico de tercer nivel: 2013 vs. 2018 / Gram-negative susceptibility patterns in a tertiary pediatric hospital: 2013 vs. 2018

Resumen Introducción: Los gramnegativos continúan siendo los causantes de infecciones asociadas a la atención a la salud (IAAS). Material y métodos:: Analizamos la resistencia antimicrobiana de patógenos durante el 2013 vs. 2018 y lo comparamos con lo publicado en 2006 vs. 2012. Resultados: Identificamos nueve patógenos gramnegativos, de un total de 404 aislamientos, con una prevalencia en 2013 (N = 227 [0.22]) vs. 2018 (N = 177 [0.17]) y una incidencia por egresos (6,607 en el 2013 y 7,778 en el 2018) del 3.4 y 2.2% respectivamente. Destacaron tres patógenos: Klebsiella pneumoniae (129 [31.93%]), Pseudomonas aeruginosa (85 [21.03%]) y Escherichia coli (80 [19.80%]). Estos, llamados patógenos ESKAPE-E, prevalecieron como causantes de IAAS. Identificamos un aumento en los patrones de resistencia para muchos patógenos en 2018. Conclusión: La multirresistencia a patógenos ESKAPE-E es un serio problema de salud pública, por carecer de alternativas terapéuticas para enfrentar este reto. Los mapas de resistencia bacteriana ayudan en la prescripción antibiótica.

Abstract Background: Gram-negatives continue to be the cause of infections associated with health care (HCAI). Material and methods: We analyzed the antimicrobial resistance of pathogens during 2013 vs. 2018 and we compare it with what was published in 2006 vs. 2012. Results: We identified 9 gram-negative pathogens, out of a total of 404 isolates, with a prevalence in 2013 (N = 227 [0.22]) vs. 2018 (N = 177 [0.17]) and an incidence due to discharges (6,607 in 2013 and 7,778 in 2018) of 3.4 and 2.2%, respectively.Three pathogens stood out Klebsiella pneumoniae (129 [31.93%]), Pseudomonas aeruginosa (85 [21.03%]) and Escherichia coli (80 [19.80%]). These, called ESKAPE-E pathogens, prevailed as the cause of HCAI. We identified an increase in resistance patterns for many pathogens in 2018. Conclusion: Multi-resistance to ESKAPE-E pathogens is a serious public health problem, due to the lack of therapeutic alternatives to face this challenge. Bacterial resistance maps help in antibiotic prescription.