Recovery from ultraviolet light-induced catabolite repression of L-arabinose isomerase
Bhatnagar, D.; Bhattacharya, A.K.
Indian Journal of Biochemistry and Biophysics 20(5): 271-275
1983
ISSN/ISBN: 0301-1208 PMID: 6327504 Document Number: 205652
UV-irradiated Escherichia coli B/r cells, when held in dark, recover from UV damage and show increased induced synthesis of L-arabinose isomerase. Photoreactivation, by illuminating the UV-irradiated cells by near UV light, brings about an increase in the capacity of the cells to synthesize L-arabinose isomerase in response to the inducer. The extent of stimulation by photoreactivation decreases with increase in time of starting the treatment. Rifampin (50 .mu.g/ml) completely stops, the stimulatory action of photoreactivation on the induced synthesis of L-arabinose isomerase in UV-irradiated cells, indicating that the increase of enzyme synthesis by photoreactivation involves new mRNA. The dark recovery of the cells from UV damage leads to an increase in cellular cAMP level along with lowering of extracellular level of the nucleotide, suggesting that cAMP from the suspending medium enters the cells. Upon dark recovery, cAMP binding activity also increases almost to the level of unirradiated cells.