RT Journal Article SR Electronic(1) A1 Feng, Peter A1 Lampel, Keith A.YR 1994 T1 Genetic analysis of uidA expression in enterohaemorrhagic Escherichia coli serotype 0157:H7 JF Microbiology, VO 140 IS 8 SP 2101 OP 2107 DO https://doi.org/10.1099/13500872-140-8-2101 PB Microbiology Society, SN 1465-2080, AB Isolates of enterohaemorrhagic Escherichia coli serotype 0157:H7 do not exhibit β-glucuronidase (GUD) activity; however, they carry nucleotide sequences for the uidA gene that encodes the GUD enzyme. Polymerase chain reaction analysis using uidA-specific primers confirmed that a genetic region homologous in size to the E. coli uidA structural gene, including the regulatory region, was present in E. coli 0157:H7 isolates. DNA sequencing analysis of the regulatory region and the 5′ terminus of the uidA gene of E. coli 0157:H7 showed a base substitution in the putative −10 promotor region and at 93 bases downstream from the initiation codon. Neither base alteration, however, appeared to affect uidA allele gene expression in the 0157:H7 isolates. Immunoblotting of cell extracts with an anti-GUD antibody showed that E. coli 0157:H7 isolates produced an antibody-reactive protein that was homologous in size to E. coli GUD, but no GUD activity was observed in cell-free extracts of these isolates. These results suggest that the antibody-reactive protein produced by E. coli 0157:H7 may be an inactive GUD enzyme. Sequencing of the uidA structural gene in 0157:H7 showed the presence of 18 additional nucleotide base substitutions, but only six altered the amino acid sequence. Also, there were two frame shift mutations, 18 bases apart, that altered the sequence of six consecutive amino acids. These genetic alterations in the uidA structural gene of 0157:H7 may account for the absence of GUD activity in this serotype., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-140-8-2101