cur-1, a mutation affecting a phenotype of sup+ strains of Escherichia coli

cur-1, a mutation found in many strains of the Y10 line of Escherichia coli K-12, but not previously described, maps at 27 min, close to galU. cur-1 causes mucoidity or uracil requirement at 29 degree C depending on the genetic background. These phenotypes are suppressed by amber codon suppressors.