INVESTIGADORES
RAPISARDA Viviana Andrea
artículos
Título:
Copper tolerance mediated by polyphosphate degradation and low-affinity inorganic phosphate transport system in Escherichia coli
Autor/es:
GRILLO-PUERTAS, M.; SCHURIG-BRICCIO, L. A.; RODRÍGUEZ-MONTELONGO, L.; RINTOUL, M. R.; RAPISARDA, V. A.
Revista:
BMC MICROBIOLOGY
Editorial:
BIOMED CENTRAL LTD
Referencias:
Lugar: Londres; Año: 2014 vol. 14 p. 72 - 82
ISSN:
1471-2180
Resumen:
Background: Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the
polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory,
Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high
polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP
levels as the involvement of low-affinity inorganic phosphate transport (Pit) system in E. coli copper tolerance.
Results: PolyP levels were modulated by the media phosphate concentration and/or using mutants in polyP
metabolism. Stationary phase wild-type cells grown in high phosphate medium were significantly more tolerant to
copper than those grown in sufficient phosphate medium. Copper addition to tolerant cells induced polyP degradation
by PPX (an exopolyphosphatase), phosphate efflux and membrane polarization. ppk−ppx− (unable to synthesize/degrade
polyP), ppx− (unable to degrade polyP) and Pit system mutants were highly sensitive to metal even in high phosphate
media. In exponential phase, CopA and polyP-Pit system would act simultaneously to detoxify the metal or one could be
sufficient to safeguard the absence of the other.
Conclusions: Our results support a mechanism for copper detoxification in exponential and stationary phases of E. coli,
involving Pit system and degradation of polyP. Data reflect the importance of the environmental phosphate concentration
in the regulation of the microbial physiological state.