[Todos] Recordatorio seminario lunes 24 de noviembre

[Cybele García]

--------------------------------------------------------------------------

>> Seminarios del Departamento de Quimica Biologica
>> Aula del Departamento de Quimica Biologica, 4to piso
>> Todos los Lunes a las 13 horas.
>> Fecha: Lunes 24 de noviembre

>> Expositor:  Lic. Pablo Iván Nikel
Instituto de Investigaciones Biotecnológicas
UNSAM-CONICET
INTI



*Metabolic flux analysis of Escherichia coli creB and arcA mutants*


*Escherichia coli* has several complex sensing mechanisms for response to
carbon availability and oxygen levels. Among them, the two-component signal
transduction systems CreBC and ArcAB are responsible for regulation of
carbon catabolism and transition from oxidative to fermentative metabolism,
respectively. To systematically investigate the contribution of CreB- and
ArcA-dependent regulation in catabolism, glucose-limited chemostat cultures
were conducted for a wild-type strain, ¦¤*creB* and ¦¤*arcA* single mutants,
and a ¦¤*creB* ¦¤*arcA* double mutant under a well-defined microaerobic
condition. Metabolic flux distributions of the cultures of these strains
were estimated based on 13C labeling experiments. It was shown that the
oxidative pentose phosphate pathway was functioning at low level under
semi-aerobic conditions for the mutant strains. Fluxes through pyruvate
dehydrogenase and the tricarboxylic acid cycle were found to be lower in the
mutants, while that of the glyoxylate shunt was higher for the
*arcA*strain. Strains bearing the
*creB* mutation achieved a higher biomass yield on glucose than that of the
wild-type strain or the *arcA* single mutant. Accordingly, the fluxes
towards biomass were higher for those strains. Taken together, these results
show that the CreBC and ArcAB systems operate in a concerted fashion to
provide a fine tuning in the central metabolic pathways of *E*. *coli*.





>> Los esperamos
>> Cybele Garcia
>> Martin Monte
>> Departamento de Química Biológica
>> Facultad de Ciencias Exactas y Naturales
>> Universidad de Buenos Aires
>> Ciudad Universitaria
>> Ciudad de Buenos Aires - Argentina