AUTOREGULATION OF PURR REPRESSOR SYNTHESIS AND INVOLVEMENT OF PURR IN THE REGULATION OF PURB, PURC, PURL, PURMN AND GUABA EXPRESSION IN ESCHERICHIA-COLI

The pur R gene encodes a repressor (PurR) controlling the synthesis of the enzymes of purine biosynthesis. The subunit of PurR was identified as a 38‐kDa polypeptide by SDS/polyacrylamide gel electrophoresis. Analysis of a pur R–lacZ transcriptional fusion indicated that pur R expression is autoregulated. This was confirmed by gel retardation and DNasel footprinting experiments, where two PurR‐binding sites were identified in the transcribed part of pur R. Introduction of a purR mutation in wild‐type and pur – lac fusion strains was found to abolish purine repression of all genes of the purine biosynthetic pathway except for pur A. Copyright © 1990, Wiley Blackwell. All rights reserved