PERSONAL DE APOYO
KRAPP Adriana Del Rosario
congresos y reuniones científicas
Título:
Dynamic NADPH homeostasis is essential to obtain maximal antioxidant protection in Escherichia coli
Autor/es:
MV HUMBERT, N. CARRILLO AND AR KRAPP
Lugar:
Tucuman
Reunión:
Congreso; Reunión Anual Nacional de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB); 2009
Institución organizadora:
SAIB
Resumen:
Bacteria
have evolved sophisticated molecular mechanisms to monitor oxidant levels and
to activate antioxidant defense genes in response to specific signals. SoxR
serves in Escherichia coli as a redox
sensing protein activated upon exposure to superoxide- generating agents such as
methyl viologen (MV), and becomes active when the 2Fe-2S cluster is oxidized.
During aerobic growth, SoxR is maintained in the inactive reduced form by a
reducing activity dependent on NADPH. When oxidized, SoxR activates the
transcription of the soxS gene. The
SoxS protein induces transcription of the soxRS
regulon, whose products act collectively to avoid and repair oxidative damage.
The aim of this work was to investigate how
directed alterations in NADP(H) levels could affect both deployment of the soxRS response and tolerance to
MV-driven oxidative stress. E. coli transformation
with a plasmid encoding a strong NADPH producer, the non-phosphorylating plant
glyceraldehyde 3-phosphate dehydrogenase, led to build-up of NADPH contents,
down-regulation of the soxRS response
and decreased tolerance to MV. Conversely, incorporation of a NADPH consumer,
chloroplast ferredoxin, resulted in the opposite behaviour. These observations
indicate that NADP(H) homeostasis plays a critical role in proper execution of
the soxRS response