The Escherichia coli heat shock regulatory gene is immediately downstream of a cell division operon: the fam mutation is allelic with rpoH

Summary Several mutations which affect critical cell functions in Escherichia coli map at 76 min on the chromosome. The genes which map in this region are the cell division genes ftsY, E, X and S, the heat shock regulatory gene rpoH/htpR/hin, the lipoprotein biogenesis gene fam and another essential gene dnaM. We determined the relative positions of most of these genes and show that the rpoH gene lies immediately downstream of the last gene (ftsX) of a cell division operon and is transcribed in the same direction. We also show that the fam-715 mutation is allelic with rpoH and so the conditional lipoprotein deficiency of the fam mutation must be due to the pleiotropic nature of the heat shock response.