Inactivation of membrane transport in Escherichia coli by near-ultraviolet light
Evidence is presented that near-ultraviolet (near-uv) light can alter galactoside transport in Escherichia coli in several independent ways. Earlier publications suggested that near-uv destroys cofactors needed for electron transport and thus places a limitation on energy reserves. In agreement, we found that the active accumulation of (/sup 14/C)thiomethyl-..beta..-D-galactopyranoside is decreased after irradiation by a larger factor than that due to action directly on the permease system. The effect on the latter was measured by the decrease in the rate of o-nitrophenyl-..beta..-D-galactopyranoside (ONPG) transport. As evidence that energy supplies for this ''downhill'' process did not become rate limiting after irradiation, we found that carbonylcyanide-m-chlorophenylhydrazone did not stimulate ONPG transport of irradiated cells. Cells genetically deficient in functional permease or cells treated with formaldehyde still transport ONPG passively, although at much lower rates. With the use of such cells, it was found that high fluences (doses) made the cells leaky. Further evidence that the permease system and the metabolic energy system can be inactivated independently is also presented. It is shown that a photoproduct from the irradiation of chloramphenicol inactivates the permease system much more efficiently than the energy system. In addition, it is shown that thio-..beta..-D-digalactopyranoside protects the permease system, but not the energy system, both against direct inactivation by near-uv and against photosensitized inactivation in the presence of chloramphenicol.
- Research Organization:
- Argonne National Lab., IL
- OSTI ID:
- 7282560
- Journal Information:
- J. Bacteriol.; (United States), Vol. 126:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CELL MEMBRANES
BIOLOGICAL RADIATION EFFECTS
PERMEABILITY
ESCHERICHIA COLI
CHLORAMPHENICOL
ENZYMES
INACTIVATION
ULTRAVIOLET RADIATION
ANTIBIOTICS
BACTERIA
BIOLOGICAL EFFECTS
CELL CONSTITUENTS
DRUGS
ELECTROMAGNETIC RADIATION
MEMBRANES
MICROORGANISMS
RADIATION EFFECTS
RADIATIONS
560131* - Radiation Effects on Microorganisms- Basic Studies- (-1987)