Western hybridization performed using anti-PpuR antibody on total cellular protein extracts. Total protein extracts were performed using different protein amounts of either parent strain P. putida WCS358 or lon mutant derivative P. putida IBE4 each carrying a plasmid expressing PpuR (pBBRppuR). Lane 1 corresponds to 10 μg of purified PpuR-6His; lane 2 and lane 3 correspond to total proteins from 2 × 107 cfu of WCS358(pBBRppuR) and IBE4(pBBRppuR) respectively; lanes 4 and 5 correspond to total proteins from 107 cfu. For lanes 4 and 5 the images were scanned using a Versadoc (Biorad) and the QuantityOne software; results of this quantification are displayed as a histogram. See text for all details.