Abstract: Wild type Escherichia coli cells as well as some mutant strains lacking specific DNA repair systems are efficiently billed upon visible light-irradiation after 5 min-incubation with meso tetra(4N-methyl-pyridyl) porphine (T4MPyP). The presence of oxygen is necessary for cell photoinactivation. The porphyrin appears to exert its phototoxic activity largely by impairing some enzymic and transport functions at the level of both the outer and cytoplasmic membrane. Thus, SDS-PAGE electrophoresis shows a gradual attenuation of some transport protein bands as the irradiation proceeds, while a complete loss of lactate and NADH dehydrogenase activities is caused by 15 min exposure to light. On the other hand, DNA does not represent a critical target of T4MPyP photosensitization as suggested by the closely similar photosensitivity of the wild E. coli and E. coli strains defective for two different DNA repair mechanisms, as well as by the lack of any detectable alteration of the pUC19 plasmids extracted from photosensitized E. coli TG1 cells.

Photosensitization of wild and mutant strains of Escherichia coli by meso-tetra(N-methyl-4-pyridyl)porphine.

GIACOMETTI, GIORGIO;IORI, GIULIO;REDDI, ELENA
1999

Abstract

Abstract: Wild type Escherichia coli cells as well as some mutant strains lacking specific DNA repair systems are efficiently billed upon visible light-irradiation after 5 min-incubation with meso tetra(4N-methyl-pyridyl) porphine (T4MPyP). The presence of oxygen is necessary for cell photoinactivation. The porphyrin appears to exert its phototoxic activity largely by impairing some enzymic and transport functions at the level of both the outer and cytoplasmic membrane. Thus, SDS-PAGE electrophoresis shows a gradual attenuation of some transport protein bands as the irradiation proceeds, while a complete loss of lactate and NADH dehydrogenase activities is caused by 15 min exposure to light. On the other hand, DNA does not represent a critical target of T4MPyP photosensitization as suggested by the closely similar photosensitivity of the wild E. coli and E. coli strains defective for two different DNA repair mechanisms, as well as by the lack of any detectable alteration of the pUC19 plasmids extracted from photosensitized E. coli TG1 cells.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2461319
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? 67
social impact