Fructose-1-kinase has pleiotropic roles in Escherichia coli.

In Escherichia coli, the master transcription regulator catabolite repressor activator (Cra) regulates >100 genes in central metabolism. Cra binding to DNA is allosterically regulated by binding to fructose-1-phosphate (F-1-P), but the only documented source of F-1-P is from the concurrent import and phosphorylation of exogenous fructose. Thus, many have proposed that fructose-1,6-bisphosphate (F-1,6-BP) is also a physiological regulatory ligand. However, the role of F-1,6-BP has been widely debated. Here, we report that the E. coli enzyme fructose-1-kinase (FruK) can carry out its "reverse" reaction under physiological substrate concentrations to generate F-1-P from F-1,6-BP. We further show that FruK directly binds Cra with nanomolar affinity and forms higher order, heterocomplexes. Growth assays with a ΔfruK strain and fruK complementation show that FruK has a broader role in metabolism than fructose catabolism. Since fruK itself is repressed by Cra, these newly-reported events add layers to the dynamic regulation of E. coli's central metabolism that occur in response to changing nutrients. These findings might have wide-spread relevance to other γ-proteobacteria, which conserve both Cra and FruK.

Fructose-1-kinase has pleiotropic roles in Escherichia coli.

In Escherichia coli, the master transcription regulator Catabolite Repressor Activator (Cra) regulates >100 genes in central metabolism. Cra binding to DNA is allosterically regulated by binding to fructose-1-phosphate (F-1-P), but the only documented source of F-1-P is from the concurrent import and phosphorylation of exogenous fructose. Thus, many have proposed that fructose-1,6-bisphosphate (F-1,6-BP) is also a physiological regulatory ligand. However, the role of F-1,6-BP has been widely debated. Here, we report that the E. coli enzyme fructose-1-kinase (FruK) can carry out its "reverse" reaction under physiological substrate concentrations to generate F-1-P from F-1,6-BP. We further show that FruK directly binds Cra with nanomolar affinity and forms higher order, heterocomplexes. Growth assays with a ΔfruK strain and fruK complementation show that FruK has a broader role in metabolism than fructose catabolism. The ΔfruK strain also alters biofilm formation. Since fruK itself is repressed by Cra, these newly-reported events add layers to the dynamic regulation of E. coli central metabolism that occur in response to changing nutrients. These findings might have wide-spread relevance to other γ-proteobacteria, which conserve both Cra and FruK.

Fatty acids can inhibit Staphylococcus aureus SaeS activity at the membrane independent of alterations in respiration.

In Staphylococcus aureus, the two-component system SaeRS is responsible for regulating various virulence factors essential for the success of this pathogen. SaeRS can be stimulated by neutrophil-derived products but has also recently been shown to be inactivated by the presence of free fatty acids. A mechanism for how fatty acids negatively impacts SaeRS has not been described. We found that unsaturated fatty acids, as well as fatty acids not commonly found in Staphylococcal membranes, prevent the activation of SaeRS at a lower concentration than their saturated counterparts. These fatty acids can negatively impact SaeRS without altering the respiratory capacity of the bacterium. To uncover a potential mechanism for how fatty acids impact SaeRS function/activity, we utilized a naturally occurring point mutation found in S. aureus as well as chimeric SaeS proteins. Using these tools, we identified that the native transmembrane domains of SaeS dictate the transcriptional response to fatty acids in S. aureus. Our data support a model where free fatty acids alter the activity of the two-component system SaeRS directly through the sensor kinase SaeS and is dependent on the transmembrane domains of the protein.

Perfil epidemiológico de los donadores de dientes humanos extraídos en establecimientos de Salud Pública, ubicados en Ahuachapán, Cuscatlán y Sonsonate, en el año 2019 / Epidemiological profile of donors of human teeth extracted in Public Health facilities, located in Ahuachapán, Cuscatlán and Sonsonate, in 2019

Determinar el perfil epidemiológico de los donadores de dientes humanos extraídos en Unidades Comunitarias de Salud Familiar de Guaymango y Barra de Santiago en Ahuachapán, San Pedro Perulapán en Cuscatlán y Salcoatitán en Sonsonate, durante el año 2019. Metodología: Investigación observacional, descriptiva y transversal en 200 pacientes donadores entre las edades de 7 a más de 60 años a quienes se les entrevistó y efectuó un examen clínico para determinar los indicadores sociodemográficos, historia médica y clínico bucal del donador y las características físicas del diente extraído. Para el vaciado, análisis e interpretación de los datos se utilizó el programa SPSS versión 25. Resultados: Del total de los pacientes donadores un 62.5% fueron de sexo femenino, el 25% entre 21 y 30 años; 84.5% reside en el área rural; 13% padece de hipertensión arterial; 21.5% presentó bruxismo, 91% caries dental y 68.5% gingivitis/enfermedad periodontal. La principal causa de extracción fue caries dental con un 61% y la pieza más extraída fue la 4-6 de éstas el 63% presentaban caries extensa y un 99% raíz completa. Conclusión: Los donadores de dientes extraídos fueron en su mayoría del sexo femenino entre 21 y 30 años de edad, del sector rural. La condición bucal prevalente fue la higiene bucal regular, caries dental y gingivitis/enfermedad periodontal. La hipertensión fue la enfermedad más encontrada en los donadores y la causa principal de extracción fue la caries dental y sus secuelas siendo la pieza 4-6 la más extraída.

To determine the epidemiological profile of the donors of human teeth extracted in Community Family Health Units of Guaymango and Barra de Santiago in Ahuachapán, San Pedro Perulapán in Cuscatlán and Salcoatitán in Sonsonate, during 2019. Methodology: Observational, descriptive and cross-sectional investigation was carried out in 200 donor patients between the ages of 7 to more than 60 years who were interviewed and performed a former clinician to determine the donor´s sociodemographic indicators, medical history and oral history and the physical characteristics of the extracted tooth. The IBM SPSS version 25 program was used TO EMPTY, analyze and interpret the data. Results: Of the total of the donor patients, 62.5% were female, 25% were between 21 and 30 years old; 84.5% reside in the rural area; 13% have high blood pressure; 21.5% presented bruxism, 91% dental caries and 68.5% gingivitis / periodontal disease. The main cause of extraction was dental caries with 61% and the most extracted piece was 4-6, the 63% of these had extensive tooth decay and a 99% had his roots complete. Conclusion: The donors of extracted teeth were mostly female between 21 and 30 years old, from the rural sector. Regular oral hygiene, dental caries, and gingivitis / periodontal disease prevailed in the oral condition. Hypertension was the most found disease in donors and the main cause of extraction was dental caries, with piece 4-6 being the most extracted.