Definition of additional flagellar genes in Escherichia coli K12.

Twenty-nine flagellar genes in Escherichia coli K12 have previously been assigned to three regions of the genome. Flagellar region I is located between pyrC and ptsG, region II between aroD and uvrC, and region III between uvrC and his. In this study, flagellar mutants in Escherichia coli K12 were obtained by selection for resistance to the flagellotropic phage, chi. They were analyzed in complementation tests using P1 phage-mediated transduction. In addition to the fla genes already described, eight more flagellar genes were identified. This analysis defined six more fla genes in region I (flaU, etc.), one more in region II (flbB) and one more in region III (flbC). Region I was shown to include at least 12 fla cistrons. Complementation analysis with polar Mu phage-induced Fla- mutants and with lambda fla phage defined four transcriptional units in region I. These were: flaU, flbA-flaW-flaV-flaK-flaX-flaL-flaY-flaM, flaZ and flaS- flaT, with transcription proceeding from left to right. The flB gene was found to be part of an operon: flB-flaI in region II. In region III, a previously unidentified gene flbC was located between hag and flaN.