4-thiouridine as the target for near-ultraviolet light induced growth delay in Escherichia coli

Abstract

4-thiouridine present in position 8 of a number of tRNAs is the chromophore to near ultraviolet light that leads to growth delay in E. coli, through 8–13 link formation. 1. i) 4-thiouridine absorption spectra and the action spectra for cross-link formation fit more closely the action spectra for growth delay than any absorption spectra of other known cellular chromophores. 2. ii) 8–13 link formation occurs in vivo. The amount of cross-linked tRNA in the cells is intimately correlated to growth delay. 3. iii) The resumption of growth of irradiated cells occur when cross-linked tRNA are no more detectable in vivo. Essentially, the growth delay is induced through inactivation of tRNA Phe, and possibly some other tRNA species.